research paper dyslexia

Defining and understanding dyslexia: past, present and future

• Oxford Review of Education 46(4):501-513
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Dyslexia is a disorder characterized by an impaired ability to comprehend written and printed words or phrases despite intact vision. It can be developmental or acquired, but in either case it interferes with academic achievement or with activities of daily living that require reading skills.

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Towards a dynamic, comprehensive conceptualization of dyslexia

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• Published: 13 January 2024

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• Maryanne Wolf 1 ,
• Rebecca J. M. Gotlieb   ORCID: orcid.org/0000-0003-2103-7809 1 ,
• Sohyun An Kim   ORCID: orcid.org/0000-0003-1718-2421 1 ,
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• Laura V. Rhinehart   ORCID: orcid.org/0000-0002-4192-132X 1 ,
• Maria Luisa Gorno Tempini   ORCID: orcid.org/0000-0002-7426-7782 2 &
• Sue Sears 3  

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Here we build from the central strength of the existing definition of dyslexia—its emphasis on neurobiological origins—and proffer a set of seven core principles for a new, more comprehensive conceptualization of dyslexia. These principles derive from two major research directions: (1) the still evolving history of attempts to explain dyslexia, including in varied writing systems; and (2) the study of the reading brain circuit, its development, and its genetic and environmental influences. What emerges from connecting these two directions is a dynamic conceptualization of dyslexia that incorporates the extensive research on the heterogeneity of dyslexia and the interdependent contributions of multiple biological and socio-cultural risk and preventive factors. A new definition of dyslexia, therefore, needs to transcend both past unitary characterizations and past assumptions based largely on the English orthography. Such a conceptualization references the ways that different languages interact with the reading brain circuit to produce different sources of reading failure. Similarly, the characteristics and consequences of dyslexia that have been considered as secondary sequela (e.g., reduced reading comprehension, social-emotional issues) should be part of a more comprehensive narrative. Of critical importance, any definition of dyslexia should clarify persisting misconceptions that associate dyslexia with a lack of intelligence, potential to learn, or talents. Thus, the overall purpose of such a definition should serve as an instrument of knowledge and an enduring reason for pursuing growth in reading for the individual, the educator, and the public.

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The Neurobiological Strands of Developmental Dyslexia: What We Know and What We Don’t Know

Revisiting the definition of dyslexia

Do we really need a new definition of dyslexia a commentary.

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Not unlike Emily Dickinson’s famous line, “Tell all the truth, but tell it slant; Success in Circuit lies” (Dickinson, 1890 , p. 506), in this paper we will approach the need for a new definition of dyslexia circuitously through two directions that intersect in a “circuit” Dickinson never anticipated. First, we will examine the insight-rich history of attempts to understand dyslexia over the last century; and second, we will connect this history to our current, evolving understanding of the reading brain circuit. Together, these different slants of knowledge provide the basis for a more comprehensive, dynamic conceptualization of dyslexia that reflects its inherent, brain-based heterogeneity and the complex impact of external, socio-emotional, and demographic variables on reading failure and reading achievement.

A history of dyslexia: “tell all the truth, but tell it slant”

Anyone who hopes to understand dyslexia through the history of its research may be flummoxed at the outset. There are few more convoluted historical records than that for dyslexia with its multiple names, definitions, and differing explanations of its underlying cognitive mechanisms. Yet, each of these names and explanations offers an insight into a given epoch’s understanding of reading and reading challenges. Just as Alberto Manguel ( 2014 ) chose to call his memorable book A History of Reading to emphasize that such a history can be told in many ways, we wish to follow his example here for the same reasons. In this way we dismiss no past research perspective for its narrower lens at that time, nor do we attempt to be inclusive in such a brief space. Rather, not unlike the story of the blind men and the elephant, we hope to show how a selected, cumulative history of the varied hypotheses unexpectedly contributes to a more comprehensive understanding of what connotes dyslexia in different individuals.

Visual and perceptual hypotheses

The fact that few phenomena have been given more differing names and more causal explanations over the last century than dyslexia has good, important reasons that will emerge later. The first use of the term “ dyslexia ” (derived from the Latin morpheme dys for ‘difficult’ and the Greek root lexis for ‘word’) by German ophthalmologist Berlin was chosen to denote difficulties with words by various adult patients. Later in the nineteenth century, two physicians, Pringle Morgan ( 1896 ) and Hinshelwood, used another term, word-blindness (derived from “Wort-Blindheit” by German ophthalmologist, Kussmaul, 1878 ) to describe an unexpected failure in children to develop reading based on an inability to see words correctly. Thus, the first causal explanations begin in the visual system, an explanation that will come in and out of this history and resurface in a more nuanced way most recently by Yeatman (e.g., White et al., 2019 ).

Neurologist Orton ( 1928 ) conducted some of the most influential dyslexia research during the early twentieth century and promptly replaced the term word blindness with the term strephosymbolia . Like others to come, Orton wished to depict what he considered to be a different underlying locus of reading failure: i.e., lateralization confusions between the brain’s two hemispheres that caused difficulties in processing symbols. In a similar vein, various neurologists and neuroscientists over time emphasized the contributions of other brain regions to indicate the role that areas like the limbic system, cerebellum (Stoodley & Schmahmann, 2009 ), and thalamus (Llinas, 1993 ) can play in visual representation, memory, and the precise timing of component parts (Wolf, 1991 ; Wolff, 1993 ) needed during reading. Again, new names like amnesia visualis verbalis for key memory issues and dyschronia for timing issues (Llinas, 1993 ) reflected the hypotheses of the researcher about what was most disruptive to the acquisition of reading in dyslexia.

Although disruptions in the visual system continued to be the predominant explanations in the first two-thirds of the twentieth century (Vellutino, 1979 ), other sensory systems were implicated in auditory processing disorders , as discussed early on by Lucy Fildes ( 1921 ) and evolved over time in several directions. For example, by mid-century, multi-modality (Blank & Bridger, 1964 ) explanations focused more attention on the connections between and among the visual and auditory systems, as well as to cognitive processes that governed these connections—like the ability to hold information in working memory and sequence verbal information. This research was the precursor for later important work on the role of executive functions in reading (e.g., Cirino et al., 2019 ; Kim, 2023 ; Swanson & Kong, 2018 ). During the 1970s, one of the most heatedly debated hypotheses, the temporal processing disorder , was rooted in speech and language pathology research and focused on the temporal, acoustic dimensions of auditory perception of the phoneme (Tallal & Piercy, 1973 ).

Phonological-based hypotheses

The most critical opponents of the latter view emerged from the field of psycholinguistics and would change the history of dyslexia. The explosion of work on the role of phonological processes in reading and in dyslexia emerged from early studies by Bond and Dykstra ( 1967 ) and from a program of research by psycholinguists working in Bell Laboratories and later Haskins Laboratories (e.g., Kavanaugh & Mattingly, 1972 ; Liberman et al., 1989 ; Liberman & Shankweiler, 1979 ; Malins et al., 2016 ). The hypothesis was that a failure within language systems, specifically phonological processes involved in the representation of phonemes and the developing meta-awareness of them, was the major linguistic source of disruption in dyslexia. This view, the phonological-core deficit hypothesis , eclipsed previous emphases on perceptual deficit hypotheses that involved visual and/or auditory systems (Vellutino, 1979 ) and became a dominant perspective till the present.

The investigations into the relationship between the phonological components of language and reading yielded significant advances in our understanding of the important role of phonemic awareness (PA) in learning the alphabetic principle in reading, as well as its utility in the early identification of reading difficulties and the teaching of beginning reading (Bradley & Bryant, 1983 ; Ramus, 2003 ; Shaywitz & Shaywitz, 2020 ; Torgesen et al., 1999 ; Washington & Seidenberg, 2021 ). The importance of phoneme-level representation in beginning reading is intrinsically connected to the alphabetic nature of the English writing system. More specifically, the ability to map the individual distinctive sounds of spoken English (i.e., phonemes) to the symbols (i.e., graphemes) representing these sounds is critical in the development of decoding and spelling. Phonemic awareness was considered such a crucial skill that it was identified by the National Reading Panel Report (NICHD,  2000 ) as one of five essential elements of effective reading instruction and is included in the goals of most interventions in dyslexia. Stretching across five decades to the present, there have been more scientific papers on this hypothesis than for any other unitary hypothesis into the causes of dyslexia (e.g., Torgesen, 2018 ; Wagner et al., 2019 ).

Neurological hypotheses

Although few today dispute the importance of phonological processes in reading and reading failure, a parallel direction of research from neurology and the cognitive neurosciences emphasized the presence of other areas of cognitive weakness causing or contributing to dyslexia symptoms. Perhaps the most influential of these hypotheses originated with the seminal research by behavioral neurologist Norman Geschwind on the “Disconnexion Syndrome in Animals and Man” (Geschwind, 1965 ). Before cognitive sciences became their own area of study, Geschwind used basic models of the brain to depict what caused acquired reading failure or alexia that resulted from discrete areas of stroke or brain injury. He used these models to convey the then novel hypothesis that different disconnections among the varied reading-related areas (e.g., vision and language regions within and between the two hemispheres) could underlie different forms of reading failure, as evident in alexia with and without agraphia .

Tucked within this overarching view of adult alexia is one of the less known aspects of developmental dyslexia's history. With these models as context, Geschwind hypothesized that color naming , which requires the connection of the visual and language systems in order to retrieve a name for abstract symbols like color, would be a powerful predictor of dyslexia in children. Color naming, he speculated, would expose the inability to connect the key reading systems to retrieve a name and thus predict dyslexia. Although by itself this hypothesis proved incorrect, his student, pediatric neurologist Denckla, and neuropsychologist Rudel went on to find that the speed of connecting these systems in naming various symbols did, in fact, predict dyslexia (Denckla & Rudel, 1976 ).

This was the beginning of two related but diverging directions of research spawned by the prolific work of Geschwind and his students, particularly Denckla and Galaburda.

Denckla pursued more cognitive-behavioral differences that could explain the predictive capacity of naming speed—that is, the rapidity of retrieval for visually presented symbols—for individuals with dyslexia. Investigating what Denckla and Rudel termed Rapid Automatized Naming (RAN), Denckla and her student Wolf (Wolf, 1991 ; Wolf & Denckla, 2005 ), along with Bowers (Wolf & Bowers, 1999 ; Wolf & Bowers, 2000a ), and multiple other researchers (see reviews in Norton & Wolf, 2012 ; McWeeny et al., 2022 ) found extensive evidence for a “second deficit” in RAN or naming speed in individuals with dyslexia. Despite efforts to explain this as a phonological-based weakness, Wolf and Bowers (Wolf & Bowers, 1999 ; Wolf & Bowers, 2000a ) demonstrated that there are children with RAN issues without PA involvement, as well as children with PA differences only. Most importantly, the most severely impaired children possessed both RAN and PA issues, among other challenges. Similar studies proliferated: e.g., using taxonomic classification methods, O'Brien et al. ( 2012 ) found analogous subtypes in a sample of 600 children. Extensive cross-linguistic research from various writing systems replicated the presence of an independent RAN weakness that was more predictive than PA in more transparent languages (Di Filippo et al., 2005 ; Ibrahim, 2015 ; Katzir et al., 2004 ; Share, 2008 ; Spencer & Hanley, 2003 ; Torppa et al., 2012 ; Traficante, 2023 ) and in other orthographies like Chinese (Tan et al., 2005 ).

There is an important, insufficiently understood historical caveat. Wolf and Bowers (Wolf & Bowers, 1999 ; Wolf & Bowers, 2000b ) first used the term “Double-Deficit Hypothesis” to include, but go beyond, unitary phoneme-based hypotheses. However, from the outset they conceptualized the three most common subtypes as placeholders for research into the various possible sources of disruption underlying RAN, as well as into multiple other vulnerabilities beyond RAN and phonology. The RAN and later RAS (Rapid Alternating Stimulus) tasks (Wolf & Denckla, 2005 ) were conceptualized then and now as assessing the speed with which various visual and language processes are connected, any one or more of which can disrupt the rapidity of retrieval (Wolf & Obregón, 1992 ). In this view, therefore, naming speed involves a mini-circuit that includes many of the same cognitive and linguistic processes in the larger reading circuit. This is the underlying basis of its predictive capacities. A RAN deficit is thus an index of various possible sources of disruption, not the actual disruptor.

Neurobiological causes of dyslexia

Work on the neurobiological and structural anatomical changes underlying dyslexia remains insufficient, but has important insights to build from, particularly the research program by Geschwind’s student, Al Galaburda. He and his colleagues pursued post-mortem, brain tissue studies as a fundamental way to understand dyslexia and other neurodevelopmental disorders (e.g., Galaburda et al., 1985 ). They (Galaburda, 1989 ) performed the first of such studies thirty years ago and showed that cytoarchitectonic changes caused by cellular migration and formation in Perisylvian regions (see also Stein, 2001 ) characterized the limited number of autopsied brains of individuals with dyslexia. Subsequently, using both brain and animal genetic models, Galaburda and his colleagues contributed greatly to an understanding of dyslexia at the cytoarchitectonic level by showing how disruptions in early cell migration in particular areas can impede later processing of written language.

These pioneering studies, although limited in sample size, provide evidence for the hypothesis that cortical development anomalies in key language-related brain regions could underlie Geschwind’s “disconnections”. These same anomalies may also underlie the lack of activation and connectivity in the neural networks associated with dyslexia on functional imaging studies (Norton & Wolf, 2012 ; Pugh et al., 2000 ).

Early and ongoing genetic studies buttress this hypothesis: for example, those genes most consistently associated with dyslexia and language processing, such as KIAA0319, are genes that regulate neuronal migration (Paracchini et al., 2006 ). Recent clinical and neuropathological studies in older patients with atypical neurodegenerative disease and selective language and reading symptoms complement this evidence. Miller and colleagues reported that patients with a form of aphasia characterized by a phonological variant show a higher rate of developmental dyslexia than the general population (Miller et al., 2019 ). The brain tissues of three of these older individuals with developmental dyslexia were recently analyzed post-mortem at the UCSF Brain bank and showed distinct cortical anomalies in well-studied language regions, in addition to the expected pathology of Alzheimer patients (Miller et al., 2019 ).

Taken together, these studies support a highly relevant hypothesis that early-life neurodevelopmental changes might influence not only educational attainment in childhood, but also life-long brain development. To be sure, we need more studies that investigate this longitudinal view, alongside the root causes of dyslexia at the histological level and the molecular biology level (see Krishnamurthy et al., 2019 ; Pugh et al., 2014 ). That said, the notion that neurodevelopmental, cortical changes can occur throughout the most complex and vulnerable areas in frontal, temporal, and parietal regions could both reconcile many of dyslexia’s history of different hypotheses described above and also help explain the heterogeneity in the subtyping research described below.

Cognitive and neuroimaging subtype research

Early neuropsychological work in the 1970s on subtypes of individuals with learning disabilities indicated the presence of discretely different characteristics not neatly explained by single causes (see Fletcher & Satz, 1985 ; Satz & Morris, 1981 ). The early subtype classifications became increasingly methodologically sophisticated through the work of Morris, Fletcher, Lyon, Francis, and their colleagues (e.g., Morris et al., 1998 ). Morris et al. ( 1998 ) completed one of the most important studies of subtypes of students with reading disability. They found nine subtypes based on students’ scores on standardized measures of PA, working memory, RAN, IQ, developmental history, and teacher reported behavior at one point in time. Like the findings by Wolf and Bowers ( 1999 ), the most impaired of their subtypes had multiple challenges, including both PA and RAN. Recent influential research by Ozernov-Palchik et al. ( 2017 ) in a group of over one thousand kindergarteners showed subgroup stability over two years. The four at-risk groups included students with weaknesses in PA, in RAN, in multiple areas including PA and RAN, and in below-average performance across all skills. There remains insufficient research on how individual subgroups change over time, particularly with appropriate intervention.

An additional, recent contribution to the research on subtypes involves brain imaging. For example, research teams headed by Gabrieli and Hoeft (Norton et al., 2014 ), Gaab and Ozernov-Palchik (Ozernov-Palchik et al., 2016 ) and Lyytinen (Lyytinen et al., 2005 ; Torppa et al., 2012 ) used brain functional imaging techniques to investigate discrete differences for different subtypes in underlying brain regions, particularly groups characterized by PA and RAN weaknesses. A different focus in a recent study using sophisticated psychophysics and neuroimaging techniques showed distinct profiles of basic auditory (non-speech sounds) and speech sound perception challenges in children with dyslexia. These profiles were associated with focal changes in specific regions of the superior temporal cortex (Qi et al., 2023 ). If these results were confirmed, they could reconcile the auditory and phonological processing hypotheses as different anatomical variants of the same condition. All of these studies provide critical links among neurobiological, neuroanatomical and clinical subtyping efforts (e.g., Norton et al., 2014 ).

Within the context of this heterogeneity have come several other new directions that involve a new look at an old hypothesis: the role of the visual system. Reminiscent of dyslexia’s “word-blindness” origins, recent work by Yeatman and his colleagues has documented the critical role of the brain’s visual word form area and visual spatial skills, such as spatial attention and the rapid encoding of visual information, in reading development (Kubota et al., 2019 ; Ramamurthy et al., 2021 ; Ramamurthy et al., 2022 ; White et al., 2019 ). The visual word form area (alternatively referred to as the occipital-temporal junction) has been at the fore of research on reading development by cognitive neuroscientists, including Dehaene and Cohen (Dehaene et al., 2004 ; McCandliss et al., 2003 ). Addressing one of the more persistent questions in dyslexia’s history, Rueckl et al. ( 2015 ) have shown in imaging studies that this brain region is implicated in dyslexia in multiple languages.

Dyslexia in languages other than English

The cumulative importance of these latter directions has direct implications for any future definition of dyslexia that goes beyond unidimensional views and indeed beyond hypotheses based solely on the English written language system. As discussed in detail early on by Aro and Wimmer ( 2003 ), by Ziegler and Goswami ( 2005 ), and more recently by Daniels and Share ( 2018 ), most studies on dyslexia, particularly those that concentrate on the phonological-deficit hypothesis, have been conducted in English. Although the ability to map the individual phonemes of spoken English to the graphemes representing these sounds is critical in the development of decoding and spelling in alphabetic writing systems, not all alphabetic writing systems are the same, and further not all writing systems are alphabetic. It is important for research in dyslexia to account for differences in the phoneme-grapheme relationships not only in shallow orthographies like Spanish, German, Dutch, Italian, and Finnish that are more transparent and consistent than deep orthographies like English and French, but also in different writing systems like Chinese and Japanese Kanji (Bolger et al., 2005 ). It is important, therefore, to acknowledge the crucial role played by cross-linguistic variations in orthographic transparency in both children’s reading development and in our understanding of dyslexia’s risk, manifestations, and progression (Kim & Petscher, 2013 ; Seymour et al., 2003 ). As one example, the important role of phonological weaknesses in the less transparent English language is not the same for children reading in more transparent languages (Anthony & Francis, 2005 ; Landerl et al., 2013 ).

By contrast, the important role of automaticity or the speed of connection between visual and language systems in reading, as indexed by RAN, appears to be more prevalent both in transparent orthographies (Georgiou et al., 2016 ; López-Escribano et al., 2018 ; Traficante, 2023 ) and in non-alphabetic writing systems like Chinese. Indeed, in investigations with Chinese subjects, Tan, Eden, Perfetti and others (Tan et al., 2005 ) likened RAN to a universal predictor because all writing systems require rapid connections between visual and language regions of the brain. In other words, RAN requires some of the same processes and same speed and seriation requirements that develop in the early reading brain’s circuit regardless of writing system. Exemplifying this in a logosyllabary, Tan et al. ( 2005 ) found that phonological awareness made a relatively weaker contribution to Chinese children’s reading development, than naming speed, writing, and orthographic awareness.

Although many subtyping efforts are based on processes underlying reading like PA and RAN, other efforts classify subtypes based on different aspects of reading performance. For example, Lovett (Lovett, 1987 ; Lovett et al., 1988 ) was one of the first researchers to classify readers on the basis of rate and/or accuracy in reading performance. More recently, Capin et al. ( 2021 ) identified three subtypes based on differences in word reading and listening comprehension deficits: moderate deficits in both word reading and listening comprehension, severe deficits in word reading but moderate deficits in listening comprehension, and severe deficits in listening comprehension but moderate deficits in word reading. Similarly, Kim and colleagues ( 2021 ) classified Korean readers into subgroups using the same analytical methods as in the Capin et al. ( 2021 ) study, but with a classification based on the severity of the deficit areas. Compton ( 2021 ) attributed such differences in Kim et al.’s ( 2021 ) criteria to the cross-linguistic difference in orthographic transparency, since Korean is more transparent in its orthography than English. The essential point that we wish to incorporate in any conceptualization of dyslexia is that both the known predictive factors and external variables, particularly language and orthography variation (Pugh & Verhoeven, 2018 ), affect our ability to predict reading development and its different forms of disruption.

Multifactorial hypotheses

In the last decade, a growing body of research on multifactorial models has been examining the effect of known predictive factors in the presence of different external factors. In multifactorial models, dyslexia, and especially its severity, is viewed as resulting from a combination of and/or interaction among risk factors, including phonological processing, RAN, and oral language problems, all of which, like dyslexia, are dimensional in nature and manifest in varying degrees of severity. Very importantly as noted by Catts and Petscher ( 2022 ), these complex interactions are also influenced by environmental factors like quality of instruction, language variation, parental support, and the individuals’ background. Thus, multi-factorial models tend to represent dyslexia as probabilistic rather than deterministic: i.e., risk factors in conjunction with protective factors increase or decrease the likelihood of dyslexia and its severity. Risk or symptomology of learning disabilities, which can include dyslexia, is increased by factors like co-morbid developmental language, attentional, or anxiety disorders (Nelson & Harwood, 2011 ), exposure to trauma (Duplechain et al., 2008 ), consciousness of reading disability stigma (Daley & Rappolt-Schlichtmann, 2018 ), and teachers misunderstanding of dialectical differences (Washington & Seidenberg, 2021 ). Conversely, there are benefits of high-quality mentoring (Haft et al., 2019 ), interventions that increase feelings of motivation (Lovett et al., 2021 ), emotional resilience (Goldberg et al., 2003 ; Zheng et al., 2014 ), and growth mindsets (Andersen & Nielsen, 2016 ), familial identity and practices concerning reading (Willingham, 2015 ), and exposure to dynamic conversations at home (Romeo et al., 2018 ). These factors can decrease dyslexia symptomology, are associated with the development of parts of the reading brain circuit, and improve students’ feelings about reading, in some case even controlling for effects of socioeconomic status. Within that context, in efforts to understand and define dyslexia, alongside known weaknesses, we must consider possible assets associated with dyslexia (e.g., Palser et al., 2021 ; Sturm et al., 2021 ) and individual strengths and protective factors. In other words, we must consider the role of changing environmental factors and social-emotional assets in the dynamic manifestations of dyslexia.

One of the very important additional variables that has emerged in multifactorial approaches concerns the genetic history of the individual and how this may contribute to children’s reading profiles. Early on, Pennington and Smith ( 1983 ) reviewed all the genetic evidence about dyslexia available at the time and documented that dyslexia is strongly heritable, associated with multiple genes, and also influenced by environment. More recently, Powers, Gaab and their colleagues discovered that home literacy environments differentially influence children’s reading profiles, based on their familial history of dyslexia (Powers et al., 2016 ).

At present there are several large-scale, genome-wide association studies that investigate more precise relationships between particular genes and specific deficits associated with dyslexia. For example, Eising et al. ( 2022 ) studied genetic relationships to word-reading, and Dębska, Pugh and their colleagues examined the influence of familial history of dyslexia in children’s neural correlates of phonological awareness (Dębska et al., 2016 ). Black, Hoeft, and their colleagues identified maternal history of dyslexia to be a risk factor for developmental dyslexia (Black et al., 2012 ). An important addition to the existing genetic studies involves the subject populations. For example, ongoing studies by members of the Gruen lab are investigating the genetic relationships of deficits like RAN in less studied populations of African-American and Hispanic-American children and other groups underrepresented in reading research (Gialluisi et al., 2019 ; Truong et al., 2019 ).

Nevertheless, as Grigorenko ( 2022 ) points out in her recent review, although genetic history is the “single dominant force shaping individual differences in reading acquisition” (p.104), more robust evidence from different countries, languages, and writing system are warranted in order to generalize the evidence on the role of these genetic factors across various cultures and populations. Within that context, recent research programs by Hoeft and by Gorno-Tempini are investigating the effects of language variation, particularly children’s early bilingual experiences, as well as genetic history, on our understanding of the important contributors to reading development and its potential disruptors. The latter include parental education and family financial circumstances as important contributors to students’ reading development and dyslexia risk.

Along similar lines, some multifactorial models emphasize not only the importance of different language backgrounds and socioeconomic circumstances, but also the different pathways in children’s reading development that are due to multiple cognitive skills involved in reading comprehension. For example, Kim ( 2017 ) used the Direct and Indirect Effect Model of Reading model to reveal that children’s working memory, theory of mind, inference, comprehension monitoring, vocabulary, grammar, word reading, and listening comprehension all collectively contributed to reading comprehension in multiple ways. Such findings are important to any conceptualization of dyslexia because they expand our understanding of reading development and failure by including language variation, the underlying roles of cognitive processes, and their combined effects on various aspects of reading, including comprehension.

Still other multifactorial studies include factors that remain insufficiently incorporated in our understanding of dyslexia, particularly protective factors like resilience and social-emotional sequelae. Risk-resilience models of dyslexia include both causal factors that put children at risk for dyslexia and resilience factors that influence more positive reading outcomes. In these models, protective factors, such as an individual’s cognitive and socio-emotional strengths and resiliency (Haft et al., 2016 ; Palser et al., 2021 ; Sturm et al., 2021 ), environmental factors such as high-quality early reading instruction (Fletcher et al., 2019 ), and the confluence of these protective factors (Gotlieb et al., 2022 ) mitigate against poor reading in at-risk populations. Risk-resilience models that consider protective factors in combination with risk factors move our conceptualization of dyslexia away from a more exclusive focus on deficits, towards the need for understanding the role of an individual’s strengths in reading outcomes.

A summary of a history of dyslexia

Examining the history of almost any conceptualization is a humbling exercise, but one with lessons that deepen our knowledge and help to guide our next steps. The history of our efforts to understand dyslexia, like the science of reading, is evolving not only with our research, but also with an understanding that each accretion of knowledge has real-life implications for the individuals with dyslexia, their teachers, families, and communities. In the next section, we examine another evolving branch of knowledge: specifically, the study of the reading brain circuit, its development, and its influences. To forecast, we believe that the coterminous examination of the history of dyslexia and the science underpinning the reading brain’s development will propel our field’s efforts to provide a more comprehensive understanding of the heterogeneous nature of dyslexia and indeed of the complexity of reading that underlies it.

A brief examination of the reading brain circuit: “success in circuit lies”

The current definition of dyslexia by the International Dyslexia Association begins by stating that “dyslexia is a specific learning disability that is neurobiological in origin.” Although much of the research cited in this paper underscores the need for revising various other aspects of the definition, particularly the emphasis on only one typical form of deficit, the neurobiological basis remains the single most important core of the definition. We will return to the other parts of the definition in our conclusions.

It is our view that an understanding of the neurobiological basis of dyslexia is best situated within an understanding of what comprises the reading brain circuit and the not-so-simple insight that our brain was never meant to read (Wolf, 2007 , 2018 ). Our ability to learn this evolutionarily new cognitive capacity required that the brain learn to build a new circuit by connecting multiple distributed regions across both hemispheres, all the lobes and layers of the brain, including the cerebellum (our evolutionarily older “little brain), and various key subcortical regions (Dehaene, 2009 ). The sum of these connected networks is a reading circuitry that has the ability to add ever more sophisticated cognitive, linguistic, and affective processes over time. Indeed, in its expert state, the original reading brain is a circuit of circuits. Further, the brain is not the only organ that supports reading; the definition states that dyslexia is neurobiological in origin, rather than neurological, in part because of the recruitment of the eyes, ears, and even viscera in reading.

We believe that the very complexity of the reading brain circuit offers another lens on why reading development is such an achievement and why it can go awry in many different ways, often as not before children even learn to read (Langer et al., 2017 ). A brief examination of several of the major precursor regions will help to underscore some of the ways that reading can be difficult for different children for different reasons from genetic to environmental. Indeed from the outset, multiple genes have been associated with dyslexia with some estimates of as much as 70% heritability of dyslexia (Erbeli et al., 2021 ). Similarly, as seen in the last section’s recent history, a range of environmental factors from family socioeconomic status, language backgrounds, to quality of literacy in the home have been shown to contribute to the experience of learning to read, to the severity of dyslexia, and to the development of the reading brain. Indeed, the major components that will make up the circuit—like visual, cognitive, linguistic, and affective processes—begin their development in the first years of life when both genetic factors and the environment are highly interactive. In reading as in life, nature and nurture influence both the precursors of reading and the various ways it can be disrupted (Gotlieb et al., 2022 ).

To begin with language, processes undergirding phonology and semantic knowledge to syntax and morphology are essential pre-reading skills that grow exponentially, depending on the language environment of the child and the family’s genetic history. Underpinning these linguistic processes are the temporal, parietal and frontal lobes of the brain with different areas specialized for different types of phonological, semantic, morphological, and grammatical knowledge. Oral language, with its involvement of speech and motor regions, requires a range of capacities that allow young children to represent phonemes in ways that differ from the way other non-speech sounds are processed. These fine-tuned phonological processes recruit multiple regions within the left frontal, temporal, and parietal lobes, such as the supramarginal gyrus, as well as right hemisphere areas responsive to aspects of oral language like rhyme and intonation (Hickok & Poeppel, 2007 ).

The contributions of visual areas, like the previously discussed visual word form area, underpin various orthographic skills that prepare the child to recognize and eventually represent the visual symbols and visual patterns of the child’s particular writing system (Borghesani et al., 2021 ). Adjacent to the visual regions is the angular gyrus, an area that Geschwind ( 1965 ) believed key to the coordination of reading-related areas and whose disruption he associated with alexia with agraphia. The angular gyrus is involved in the connection and translation of visual information processed in the occipital region to semantically comprehensible input in the temporal regions (Pugh et al., 2000 ).

The cognitive components that contribute to the reading circuit include myriad areas involved in executive function processes like working memory to the formation and consolidation of background knowledge in long-term memory within various areas, particularly the medial temporal gyrus. The effortful control of attention and the ability to direct and focus it is another pre-reading skill that is associated with a frontoparietal network of cortical, subcortical and mid-layer regions in the brain.

Still another set of precursor skills that require more emphasis in the early reading circuit are the contributions of emotional engagement and the forerunners of introspection, both of which help the developing pre-reader make important affective associations to reading, as well as learn to think carefully about stories and ideas heard from books read to them. As discussed by Wolf ( 2007 , 2018 ), these associations provide not only the ideal foundation for reading development, but also a protective factor that can affect the severity of dyslexia. The insula, buried deep within the cortex, is a critical part of the reading brain that is associated with making these strong emotional associations with reading, and, in conjunction with prefrontal structures, supports the growth of reflection and the child’s own thinking over time.

Although the development of each and all of these precursor processes is evidence enough of the complexity inherent in reading development, the circuit cannot function properly without processes responsible for the rapid deployment and temporal coordination of these precursor regions with each other. Only when each component can work together at almost automatic speeds will fluent decoding and fluent comprehension become possible. The thalamus, a subcortical area of the brain, and the cerebellum are both critical for the precise timing and temporal integration of all the components of the reading circuit, just as the angular gyrus and other connective regions are involved in their coordination.

With the help of neuroscientist, artist, and cerebellum expert Catherine Stoodley, Fig. 1 provides a schematic representation of the major regions underlying processes involved in the reading brain circuit.

Regions in the reading brain circuit

The overarching leitmotiv of this brief overview and of Fig. 1 ’s depiction is that written language is a stunning example of the brain’s ability to make all manner of new connections that were never genetically programmed like oral language and vision. The reading circuit represents an extraordinary leap forward in the brain’s use of its neuroplasticity to make new circuits for novel human inventions like literacy and numeracy. The complexity and the plasticity of the new circuit, however, contribute to both its Achilles-like strength and vulnerability. For, with such complexity and neuroplasticity-based adaptational ability, no one source of disruption and no one environmental influence will be sufficient to capture all forms of its failure in all individuals. Just as the history of dyslexia is pockmarked by various explanations, the circuit is subject to different causes of disruption or failure and different influences.

Bringing history and the reading brain circuit together

Returning to our initial use of Emily Dickinson’s “circuitous” approach to truth, we wish now to connect the two sections of this paper. In Fig. 2 , we have graphed many of the names used in the history of dyslexia onto the reading brain circuit. Note that when the various names for dyslexia over the last century and a half are mapped on the underlying regions, they provide a surprisingly close approximation of the reading brain circuit. In other words, if something can go wrong in the reading brain circuit, at some point in the history of dyslexia, it has gone awry and become the basis of the next new name and next causal hypothesis. The two sections of this paper converge to provide the basis for the heterogenous nature of dyslexia, the first of several principles that go beyond the original definition of dyslexia.

A Map of the history of explanations for dyslexia

By looking at both history and the reading brain circuitry together, there are several principles that we believe are key for a new conceptualization and eventual definition of dyslexia. First, there will be different manifestations of dyslexia depending on what is most vulnerable in the circuit for a given language. Although the natural desire in science for parsimony has made the more unitary hypotheses of dyslexia dominate its history, the cumulative history of dyslexia and the reading brain itself reveal that there will be no single form of dyslexia, an understanding further confirmed by cross-linguistic and cross-writing system studies. There will be different profiles of characteristics among children with dyslexia across languages with weaknesses in phoneme awareness, the processes underlying RAN, and potentially other language, visual, and executive functions presenting in different combinations, depending on the writing system (Daniels & Share, 2018 ; Share, 2021 ).

Second, the reality that dyslexia is developmental and influenced by both genetic and environmental factors adds further complexity. The influences of language variation and language/literacy background, cultural heritage, type and intensity of instruction and intervention will impact how dyslexia manifests in a given individual over time. Although dyslexia can be effectively remediated, especially when the particular areas of weakness are identified early on in individual learners (Lovett et al., 2017 ; Ozernov-Palchik & Gaab, 2016 ), the neurobiological differences in the brain’s organization remain largely the same across the lifespan. It is in this sense that dyslexia is not so much a reading disorder, but rather a different organization of the brain. This organization disadvantages the acquisition of the human species’ relatively new invention of reading through various disruptions to the reading circuit, including neurodevelopmental anomalies before the circuit is formed, as well as can give advantages in other arenas when enabled to do so.

Third, and an outgrowth of the second principle, the differences in brain organization that have historically been conceptualized largely in terms of weaknesses and deficits should be researched and described in conjunction with concomitant strengths and explicitly disassociated with any lack of intelligence. Indeed, the areas of weakness will be impacted by the opportunities individuals with dyslexia have to develop their potential strengths, particularly in visual-spatial skills (Schneps et al., 2012 ; Von Karolyi et al., 2003 ; Wolff & Lundberg, 2002 ), interpersonal skills (Palser et al., 2021 ; Sturm et al., 2021 ), and declarative memory (Hedenius et al., 2013 ). Currently, research into educational practices to support the strengths associated with dyslexia is still limited, especially for marginalized youth (Blanchett, 2010 ). Although there is some evidence to suggest that dyslexia is not associated with greater creativity (Erbeli et al., 2022 ), the history of individuals with dyslexia illustrates the over-representation of people with dyslexia in the arts, entrepreneurship, and other professions that rely on abilities to think and perceive “outside the box” (Logan, 2009 ). Therefore, asset-based teaching pedagogies for students with dyslexia (Orkin et al., 2022 ) must be further explored in future research.

It is critical to the societal understanding of dyslexia that, although it is typically described as a specific learning disability, dyslexia is a learning difference that becomes a disability to the extent that environments are disabling. There are social and emotional sequela often associated with environments that make students feel ashamed or lacking in intelligence. Noted long ago by Orton and by Geschwind ( 1982 ) in a paper memorably titled “Why Orton was Right”, there is a greater vulnerability to mental health challenges such as anxiety and depression (Maughan & Carroll, 2006 ; Sturm et al., 2021 ) among individuals with dyslexia. It is essential, therefore, both for the public and for the individuals with dyslexia that the content of our definition helps to combat negative stereotypes about dyslexia and appreciate the role of environment, including educational and socioeconomic context, in contributing to dyslexia.

Such a definition should ensure that teachers, parents, and students know that individuals with dyslexia are lacking neither in intelligence nor potential talents; and that with appropriate, evidence-based, structured literacy interventions, particularly those with emphases on resilience, persistence, and esteem (Gotlieb et al., 2022 ; Haft et al., 2016 ; Hendren et al., 2018 ; Lovett et al., 2017 , 2022 ; Lyon & Goldberg, 2023 ; Morris et al., 2012 ; Rappolt-Schlichtmann et al., 2018 ), they can and will learn to read, even when early environments did not provide optimal supports. The history of rigorous reading intervention studies in the last twenty years underscores how well we can remediate children at risk for dyslexia, regardless of their race, socioeconomic background, or IQ. There are no silver bullets to intervention, but individuals with dyslexia can and will learn to read, particularly when provided interventions that are early, evidence-based, structured, multicomponential, and explicitly taught (Lovett et al., 2017 ; Lovett et al., 2022 ; Lyon & Goldberg, 2023 ; Morris et al., 2012 ). In the process, such interventions increase the social-emotional wellbeing of struggling readers (Traficante et al., 2017 ).

Conclusions: Towards a dynamic, comprehensive conceptualization of dyslexia

The history of our understanding of dyslexia has continuously been evolving, just as is our research into the reading brain circuit’s complex origins and its potentially even more complex future in the digital culture. What is constant is change , not only in our concepts of dyslexia, but also within how individuals with dyslexia change over time according to how they are taught, how they are perceived, and how their individual strengths are enabled by society. Thus, the very definition of dyslexia itself must be dynamic and designed to change with newer knowledge and ever more sophisticated and comprehensive insights into its diagnosis and instruction. Here, we have discussed the existence of different subtypes of dyslexia that may depend on an individuals’ unique neurodevelopmental profile, language system, social-emotional and environmental factors, strengths, and preventative factors. Although the prevalence of particular subtypes of dyslexia may vary over time and context, the heterogeneity of dyslexia will persist.

Our contributions to efforts to construct a new definition will be in the form of principles we hope will be embedded by those ultimately responsible for writing this definition.

Dyslexia represents a unique organization of the human brain that is characterized by both disadvantages and advantages, both of which are influenced by neurodevelopmental, genetic, and environmental factors that have no relationship to intelligence.

The most common disadvantages include unexpected difficulties in the acquisition of accurate and/or fluent reading, spelling, and comprehension.

The most common predictive factors include independent or combined weaknesses in phonological components of language and processes indexed by naming speed, either of which can co-occur with multiple other factors such as executive function and visual-orthographic-related processes.

There will be different manifestations of dyslexia depending on what is most vulnerable in the reading circuit for a given language and writing system.

Both the risk for and developmental course of dyslexia are influenced by social, emotional, and environmental factors that range from socioeconomic background and language variation to emotional vulnerabilities and educational experience.

Although typically classified as a specific learning disability, dyslexia should never be associated with a lack of intelligence, talent, or effort. With appropriate, evidence-based, structured literacy instruction that is provided as early as possible, individuals with dyslexia can learn to read and develop their full potential.

Dyslexia can change over time, particularly when the strengths and advantages of its unique differences in brain organization are fostered alongside preventive factors that emphasize resiliency, persistence of effort, and respect for the potential of every individual.

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Wolf, M., Gotlieb, R.J.M., Kim, S.A. et al. Towards a dynamic, comprehensive conceptualization of dyslexia. Ann. of Dyslexia (2024). https://doi.org/10.1007/s11881-023-00297-1

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ORIGINAL RESEARCH article

Dyslexia: a bibliometric and visualization analysis.

• 1 Institute of Information Resource, Zhejiang University of Technology, Hangzhou, China
• 2 Library, Zhejiang University of Technology, Hangzhou, China

Dyslexia is a disorder characterized by an impaired ability to understand written and printed words or phrases. Epidemiological longitudinal data show that dyslexia is highly prevalent, affecting 10–20% of the population regardless of gender. This study aims to provide a detailed overview of research status and development characteristics of dyslexia from types of articles, years, countries, institutions, journals, authors, author keywords, and highly cited papers. A total of 9,166 publications have been retrieved from the Social Sciences Citation Index (SSCI) and Science Citation Index Expanded (SCI-E) from 2000 to 2021. The United States of America, United Kingdom, and Germany were the top three most productive countries in terms of the number of publications. China, Israel, and Japan led the Asia research on dyslexia. University of Oxford had the most publications and won first place in terms of h-index. Dyslexia was the most productive journal in this field and Psychology was the most used subject category. Keywords analysis indicated that “developmental dyslexia,” “phonological awareness,” children and fMRI were still the main research topics. “Literacy,” “rapid automatized naming (RAN),” “assessment,” “intervention,” “meta-analysis,” “Chinese,” “executive function,” “morphological awareness,” “decoding,” “dyscalculia,” “EEG,” “Eye tracking,” “rhythm,” “bilingualism,” and “functional connectivity” might become the new research hotspots.

Introduction

The term dyslexia is derived from the Greek script and was first proposed in 1887 by Dr. Rudolf Berlin in his work “Eine besondere Art der Wortblindheit (Dyslexie)”. In 1994, Lyon proposed a working definition of dyslexia, and later in 2002, a revised version of dyslexia was approved as “dyslexia is a specific learning that is neurobiological in origin that is characterized by difficulties with accurate and/or fluent word recognition and by poor spelling and decoding abilities” ( 1 , 2 ). In 1896, Hinshelwood J. published a case of dyslexia ( 3 ). There were almost no publications on dyslexia from 1900 to 1945 and the possible reason might be the turmoil of society and the world wars. Since 1946, more scientific research gradually uncovers the reasons behind dyslexia including the causes, symptoms, clinical diagnosis, and improvement measures ( 4 – 13 ). Although the root cause of dyslexia is still unclear, researchers do have some explanations that give us a better understanding of dyslexia and people with dyslexia ( 14 – 21 ). According to the European dyslexia association (EDA), the incidence of dyslexia worldwide is about 9–12%. At present, some countries have passed a series of legislation to promote better identification of people with dyslexia, and to protect the rights in education, employment, and access to public services of individuals with dyslexia ( 22 – 25 ).

Bibliometrics was proposed by Alan Pritchard in 1969, defined as “the application of mathematics and statistical methods to books and other media of communication” ( 26 ). Bibliometrics is an important branch of information science and philology. At the same time, it also shows important methodological value and becomes a special research method of information science. The number of bibliometrics academic papers published each year around the world is continually increasing, with about 3,000 in 2021. Bibliometric analyses are useful tools to quantitatively analyze academic literature to get a good understanding of the research trends in specific areas of science and technology, such as public health care ( 27 – 32 ), drug discovery ( 33 – 35 ), nursing ( 36 , 37 ), biomass ( 38 – 42 ), and COVID-19 ( 43 – 49 ). Bibliometrics has become an academic link closely related to science communication and basic theories. To our knowledge, few comprehensive bibliometric studies have been performed on the dyslexia research literature. Ram ( 50 ) conducted an analysis of dyslexia literature (1967–2016) from Scopus, which mainly studied the document types, trends of the number of publications, most productive countries, journals, authors, and keywords. Recently, Zhang et al. ( 51 ) published a paper on the top 100 most-cited studies of dyslexia research. Due to the language and the stages of cognition of dyslexia, there is still a need to carry out a comprehensive analysis on the differences of bibliometric characters and research priorities and hotspots of dyslexia research from a country perspective.

To fill this research gap, this study (1) uses the bibliometric method to indicate the status and development trends using major research areas, productive institutes, and journals from a country perspective, (2) analyzes the collaboration patterns between countries and organizations, (3) explores the priorities and hotspots by analyzing the author keywords from temporal evolution and a country perspective. This study demonstrates the status of studies of dyslexia from a country perspective, which offers readers a fresh perspective and suggestions to dyslexia students and families, researchers, and policymakers for future challenges and policy formulation.

The analysis was based on the publications related to “dyslexia” which were retrieved through the Social science citation index (SSCI) and science citation index expand (SCI-E) during the period 2000 to 2021. The data were obtained from the Web of Science (WoS) Core Collection by searching the title, abstract, author keywords, and KeyWords plus with search formula of “dyslexia” on January 14th, 2022. The graphical analysis of cooperation uses bibliographic coupling, co-citation, citation, co-authorship, and co-occurrence metrics. We used the Derwent Data Analyzer (DDA) software to present the outcomes of bibliometric analyses. Articles originating from England, Scotland, Wales, and Northern Ireland were grouped under the United Kingdom (UK) heading. The impact factor (IF) for each journal was determined according to the report from the 2020 Journal Citation Reports (JCR). Note that some related publications that did not use “dyslexia” in their topic parts may not be included in this analysis. This issue might produce some deviations.

General Statistics

In total, 9,166 papers were obtained from the WoS, including 14 article types. They were articles (7,651), review articles (589), meeting abstracts (409), editorial materials (262), proceedings papers (248), early access (127), letters (101), book reviews (97), corrections (31), book chapters (24), news items (21), biographical-items (4), retracted publications (2), and reprints (1). The vast majority of publications were published in English (8,776; 95.745%), followed by German (197; 2.419%), French (79; 0.862%), Spanish (62; 1.480%), Portuguese (12; 0.131%), Czech (10; 0.109%), and others (30; 0.330%). The following analysis was based on the top eight document types which are the majority of the publications in this field.

Total 99 countries have published articles on the topic of dyslexia from 2000 to 2021. Figure 1 show the annual analysis of published papers of the top 10 most productive countries. The United States of America published the most articles (2,589) and the highest h-index (148). United Kingdom was in the second position with a total of 1,811 publications. Other productive countries included Germany (721), Italy (648), Canada (598), China (564), France (558), Australia (506), the Netherlands (445), and Israel (380). From 2000 to 2007, the annual output of publications in China did not exceed 10. Thereafter, the number of publications increased rapidly and reached 59 in 2020. In summary, no countries from Africa, and although publications from Asia countries (China and Israel) have increased quickly in the past 10 years, publications from the United States of America and European countries have dominated the dyslexia research field because of their longer accumulation of expertise.

Figure 1 . The number of publications per countries by year.

International Cooperation Analysis

The academic collaboration networks of countries were extracted using Derwent Data Analyzer (DDA) software based on the co-occurrence matrix of author's country and country cooperation. The result of the top 20 most productive countries' cooperation (with a minimum of 5 shared publications) is shown in Figure 2 . The size of nodes represents the number of publications. The lines between the nodes represent the cooperative frequency. The United States of America is the country with the highest number of papers in the dyslexia research field, followed by the United Kingdom, Germany, Italy, Canada, and China. As can be seen in Figure 2 , the United States of America cooperated most frequently with the United Kingdom, Canada, and China. Furthermore, the United States of America and United Kingdom had the biggest collaboration network among the top 20 most productive countries. Researchers from Japan, Brazil, and Greece need to strengthen their international cooperation. China, Israel, and Japan led the research in Asian countries.

Figure 2 . Collaborative relationships among the top 20 most productive countries.

Organization Co-occurrence Analysis

A total of 4,869 organizations have published papers on the study of dyslexia. The top 15 most productive organizations concerning the number of publications and h-index have been enlisted in Table 1 . The University of Oxford ranked first in terms of total publications and obtained the highest h-index (75), followed by UCL and the University of Jyvaskyla. Yale University has the highest number of ACCP. Figure 3 shows the cooperation between organizations with a minimum of 8 papers among the top 50 productive organizations. As shown in Figure 3 , institutions from the same country were more closely connected. This was confirmed by the analysis of the top 3 most collaborative organizations for each institution (see Table 1 ). The University of Oxford has the largest collaborative network.

Table 1 . The top 15 most productive organizations of publication, citations and h-indices during 2000–2021.

Figure 3 . Collaborative relationships among the top 50 most productive organizations.

In addition, we analyzed the share of cooperative publications between institutes (see Table 1 ). It can be seen that all the 15 most productive institutions except University Haifa have very high collaboration rates, especially the UCL, Harvard University, Yale University, and the University of Connecticut. Interestingly, all of the top 15 prolific organizations are universities. It suggests that dyslexia research is mostly held by universities.

Prolific Authors' Analysis From a Country Perspective

There are 17,009 authors who have published at least one paper on the research of dyslexia. Table 2 outlines the top 20 contributing authors based on the number of publications they authored or co-authored. As can be seen in these data, all of the authors are from the top 20 productive countries. Among the top 20 prolific authors, five authors are from the united States of America, four from United Kingdom, two from Finland, P. R. China, Belgium, and Italy, and one from Germany, the Netherlands, and Austria. Schulte-korne G. ranked first on the list with the highest number (101) of dyslexia papers, Snowling MJ obtained the second one with 99 papers, and Lyytinen H obtained the third one with 95. For the average citation per paper, Fletcher JM ranked first with 99.63, followed by Pennington BF (86.49) and Bishop DVM (81.98). Looking to the H-index record, Lyytinen H obtained the first position with 45, followed by Snowling MJ, Goswami U, and Pennington BF. It is worth noting that three out of four United Kingdom researchers are from the same institution, the University of Oxford. Once again it proved the outstanding contribution of the University of Oxford to dyslexia research.

Table 2 . The top 20 most productive authors of publication, and h-indices during 2000–2021.

Schulte-korne G. is from Ludwig-Maximilians-University of Munich and his main research areas in dyslexia include genetics ( 52 – 56 ), assessment ( 57 , 58 ), intervention ( 59 – 62 ), language ( 63 , 64 ), and cognitive neuroscience ( 55 , 65 , 66 ). Snowling MJ, listed in the second place, is from the University of Oxford and her research on dyslexia focuses on language impairment ( 67 – 69 ), comorbidity ( 70 , 71 ), and intervention ( 72 – 76 ). Lyytinen H is from the University of Jyvaskyla and his research on dyslexia focuses on the longitudinal study ( 21 , 77 – 79 ), speech perception ( 80 – 82 ), auditory processing ( 83 – 85 ), and intervention ( 86 , 87 ).

Research Area and Journal Analysis From a Country Perspective

Research works on dyslexia have been carried out in about 101 research areas in SCI and SSCI databases. Figure 4 shows the number of papers published by the top 20 most productive countries in the top 20 most productive research areas. “Psychology” ranked first in terms of the total publications of all countries. “Neurosciences Neurology” and “Education Educational Research” are listed in the second or third position in all countries. Sweden, Spin, Norway, the Netherlands, China, and Greece had published more papers on “Education Educational Research” than “Neurosciences Neurology”.

Figure 4 . Number of papers in the top 20 research areas by the top 20 most productive countries.

The 9,110 papers related to dyslexia research during 2000–2021 were published in 1,156 journals. Table 3 shows the number of papers published by the top 15 most productive countries in the top 10 most productive journals. About 30% of articles were published in these top 10 productive journals in the top 15 countries. Dyslexia published the most articles in this research field (415 publications), followed by Neuropsychologia (302), Journal of Learning Disabilities (296), and Frontiers in Psychology (280). United Kingdom published the most articles in Dyslexia while United States of America published more articles in the Journal of Learning Disabilities and Annals of Dyslexia than other countries. These suggested that the United Kingdom and United States of America researchers prefer to publish in journals hosted by their countries.

Table 3 . Number of papers in the top 10 Journals and by the top 15 most productive countries.

An Analysis of Author Keywords From a Global Perspective

Keywords analysis has been used widely to analyze research hotspots and trends ( 88 – 93 ). To identify the research focus of dyslexia research, 9,562 author keywords which appeared 32,757 times from 9,110 papers were analyzed. Keywords with the same meanings were grouped and represented by one unified word or phrase, and the publications that lack author keywords may not be included in this analysis. Among the author keywords, 6,705 (70%) were used only once. The high percentage of once-only author keywords may indicate a lack of continuity in research and a wide range of interests in dyslexia research.

Figure 5 shows a network map of author keywords co-occurrence analysis (frequency not <50 times) related to dyslexia. As seen in the analysis result in Figure 5 , the keywords “dyslexia” and “reading” occupied the core positions. The top high-frequency nodes linked with “dyslexia” are “reading,” “children,” “attention,” “dyscalculia,” “magnocellular,” “adults,” “magnetoencephalography,” and “MRI”. Keywords “fMRI,” “eye movements,” “spelling,” “intervention,” “phonology,” and “writing” were the top high-frequency nodes connected to “reading”.

Figure 5 . Globe research hot points related to dyslexia.

To better understand the development trend of research, we compared the top 50 high-frequency author keywords in the past 5 years and the first 16 years (see Table 4 ); “dyslexia” and “developmental dyslexia” were exceptions because these keywords were among the search terms of the data that were used in this study. “Phonological awareness,” “reading,” and “spelling” are the main research aspects; “children” are the main group studied. “fMRI” was still a strong and useful technique to measure the brain activity of dyslexia and remained among the top eight most frequently used keywords ( 94 , 95 ). “Literacy” refers to the quality or state of being literate, especially the ability to read and write. The rank of “literacy” increased from 27th in 2000–2016 to 15th in 2017–2021, suggesting that the research of literacy remained hot research during the past 20 years.

Table 4 . Temporal evolution of the 50 most frequency used author keywords.

With the in-depth research and experience accumulation of dyslexia, early intervention and prevention of dyslexia have important social significance ( 96 ). “Rapid automatized naming (RAN)” as one of the effective cognitive measures drew the attention of researchers that involved in creating optimal assessments and interventions ( 97 ). In fact, the rank of “Rapid automatized naming” had an apparent upward movement from 37th in 2000–2016 to 27th in 2017–2021. Both “Assessment” and “intervention” also had a big upward movement from 40th in 2000–2016 to 29th in 2017–2021 and 36th in 2000–2016 to 21st in 2017–2021, respectively. In 1976, Gene Glass first used the name “Meta-analysis” to represent the process and method of integrating and analyzing many empirical studies on the same subject through statistical analysis to obtain the most representative conclusions. This method had become an important tool for analyzing various research results of dyslexia ( 98 – 101 ) and “meta-analysis” reached the 30th in 2017–2021 from 95th in 2000–2016.

In the 1980s and 1990s, Chinese scholars began to study dyslexia in reading Chinese, but most of the results were published in their Chinese journals. In recent years, with the enhancement of scientific research capabilities and international cooperation, increased research results have been published in international journals ( 102 – 106 ). The rank of “Chinese” had a dramatic increase from 49th in 2000–2016 to 32nd in 2017–2021. It is also worth mentioning that “executive function” ( 107 , 108 ), “morphological awareness” ( 109 , 110 ), “Meta-analysis,” “decoding” ( 16 ), “dyscalculia,” “EEG” ( 111 , 112 ), “Eye tracking” ( 113 , 114 ), “rhythm” ( 115 , 116 ), “bilingualism” ( 117 , 118 ), and “functional connectivity” ( 119 , 120 ) entered the top 50 high-frequency keywords in 2017–2021, suggesting that these topics may become the new research hotspots.

An Analysis of Author Keywords From a Country Perspective

Table 5 shows the 20 countries with the highest scientific production in dyslexia research as well as the keywords most used by these countries. Not surprisingly, “dyslexia,” “reading,” and “developmental dyslexia” were the keywords most used by most of these countries, ranking first to third in 15 of the 20 countries. “fMRI” was one of the research hotspots in the United States of America, Norway, Switzerland, and Austria. The language of early research on dyslexia was mainly English. In the 1970s, some researchers believed that the writing system of Asian countries would not cause dyslexia. However, with the development of early reading education activities by educators in some Asian countries, the problem of children's dyslexia had gradually attracted the attention of researchers. Therefore, it was not surprising that Asian countries (China, Japan, and Israel) had their language as one of their research focuses ( 104 , 121 – 128 ).

Table 5 . Top 5 most used author keywords by top 20 most productive countries.

An Analysis of Highly Cited Papers Based on WoS

The citation account is an important indicator of academic influence and was widely used in research evaluation. According to the Essential Science Indicators (ESI) database, highly cited papers (HCPs) refers to papers with citations in the top 1% of all papers based on a cited threshold for an academic field and publication year during the past 10 years. To some extent, HCPs from the ESI database might reflect research directions and hotspots in an academic field ( 129 ). Table 6 shows the HCPs of dyslexia over the last 10 years. One was published in the Lancet (IF = 79.323 in 2020) and Nature Reviews Neuroscience (IF = 34.87 in 2020). Two were published in the Annual Review of Psychology, Journal of Learning Disabilities , and Trends in Cognitive Sciences , respectively. Among the 16 HCPs, seven papers included authors from the United States of America and the United Kingdom, two from Germany, Finland, and Norway, and one from Finland, China, Austria, France, Hungary, Switzerland, and the Netherlands. It is worth mentioning that China was the only non-European and non-United States country, indicating that China has strengthened its development in this field of research. Among the 16 HCPs, two were about Rapid Automatized Naming (RAN) ( 97 , 130 ) and two about meta-analysis ( 100 , 101 ), indicating that RAN and meta-analysis became the hotspots in dyslexia research. “Predictors of developmental dyslexia” ( 131 ) and “Early detection of dyslexia risk” ( 96 ) might be one of the new dyslexia research directions.

Table 6 . Highly-cited papers of dyslexia.

There is no doubt that more countries have taken dyslexia seriously over the past few decades. The United States of America, United Kingdom, and Germany had done well in publishing research papers in this field. Some Asian countries like China and Israel have started to play a role in dyslexia research. It is worth noting that in 2020–2021, the research results from China increased significantly, and the ranking jumped to third place based on the number of published papers in the past 2 years.

North America, Western and Northern Europe, Asia, and Australia were the most active regions in the research of dyslexia. This was further confirmed by most active institutions and authors. There were no organizations from Africa in the top 15 most productive institutions that indicated that the issues relating to dyslexia in low-income regions lag far behind in developed countries and regions. The possible reason might be poor awareness of dyslexia among educators, the public, funding input, economic level, etc. As dyslexia is a world health issue, we expect more Asian and African nations join this research area. Although, most of the dyslexia research is held by universities, it will benefit sharing its knowledge and experiences between organizations such as hospitals, schools, and research centers.

According to the keywords analysis, 65% of publications were about children, suggesting that the most of research was about children with dyslexia. At present, MRI technology is mostly used to explore the brain function and mechanism of dyslexia, among which fMRI research is at the forefront. As can be seen from Figure 5 and Tables 4 , 6 , “developmental dyslexia,” “phonological awareness,” children, and fMRI are still the hotspots in dyslexia research. By comparing the keywords in papers published before and after 2017, we found that the keywords “literacy,” “rapid automatized naming (RAN),” “assessment,” “intervention,” “meta-analysis,” “Chinese,” “executive function,” “morphological awareness,” “decoding,” “dyscalculia,” “EEG,” “Eye tracking,” “rhythm,” “bilingualism,” and “functional connectivity” were increasingly attracting the attention of researchers and had become some new research hotspots in dyslexia research. With the rapid development of the Internet, more knowledge is mainly obtained through network resources, and the effect of dyslexia on “information seeking” behavior has gradually attracted the attention of dyslexia researchers ( 132 , 133 ). In addition, the emergence of a new keyword COVID-19 in the past 2 years also showed that during the COVID-19 epidemic, researchers began to study the impact of the epidemic on dyslexia research ( 115 , 134 – 137 ). As the international exchange of dyslexia research continues to grow, scientists are aware that differences in education-related legislation in different countries may lead to persistent differences between psychologists' assessment practices. “Methods used by psychologists for identifying dyslexia: A systematic review” by Sadusky et al. ( 138 ) drew a conclusion that “a consensus operational definition of dyslexia and universal assessment guidelines” is needed. At the same time, the public library, as one of the important places for people to read, has thought about how to better serve dyslexic users ( 139 , 140 ).

Conclusions

In this study, we presented a general overview of the dyslexia research area from a country perspective. The number of countries participating in dyslexia research increased to 68 in 2021 from 32 in 2000. In total, 99 countries published papers in this research field since 2000. All 9,110 publications were analyzed based on co-occurrence of country, institution, author, and author keyword. The United States of America, United Kingdom, and Germany were the top three most prolific countries and had the biggest collaboration network in the dyslexia research. Currently, international cooperation is still insufficient in Asian and African countries. The advanced expertise and experience of developed countries can be shared with developing countries through international cooperation. To our knowledge, there is no cure for dyslexia, but early assessment and intervention will give the best outcome. And also, people with dyslexia can learn to read with structured literacy which helps to rewire their brains. This was confirmed by the topmost used author keywords “intervention,” “assessment,” and “literacy”.

This study provided an insight into the status of current dyslexia research. It can also provide useful information for relevant researchers to find potential collaborators. In addition, this study may help to increase public awareness and acceptance of dyslexia, disseminate knowledge of dyslexia to educators, policymakers, and especially parents of children with dyslexia.

Data Availability Statement

The original contributions presented in the study are included in the article/supplementary material, further inquiries can be directed to the corresponding author/s.

Author Contributions

YWan and YC designed the study. WY is responsible for data collection. YC and XY analyzed the data. YWu analyzed, interpreted the data, and wrote the manuscript. All authors have read and agreed to the published version of the manuscript.

This research was funded by National Social Science Foundation of China (20BTQ028), the Scientific Research Program of Zhejiang Educational Committee (Y202147067), and Humanities and Social Sciences Research Foundation of Zhejiang University of Technology (SKY-ZX-20200076).

Conflict of Interest

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Publisher's Note

All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.

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Keywords: dyslexia, children, health, bibliometric, keywords analysis

Citation: Wu Y, Cheng Y, Yang X, Yu W and Wan Y (2022) Dyslexia: A Bibliometric and Visualization Analysis. Front. Public Health 10:915053. doi: 10.3389/fpubh.2022.915053

Received: 07 April 2022; Accepted: 24 May 2022; Published: 23 June 2022.

Reviewed by:

Copyright © 2022 Wu, Cheng, Yang, Yu and Wan. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY) . The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

*Correspondence: Yanxia Cheng, chengyanxia74@zjut.edu.cn ; Yuehua Wan, wanyuehua@zjut.edu.cn

Disclaimer: All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.

Untangling dyslexia myths and misconceptions

Vol. 55 No. 6 Print version: page 40

• Learning and Memory
• Disabilities

• There is no link between dyslexia and IQ.
• Promising research showing the differences in dyslexic brains may lead to more objective testing and treatments.
• With early and effective interventions—and absent any other disability—all children can learn to read.

When Tim Odegard was a third grader struggling to learn to read, his parents were told that his IQ score made him “too stupid” to have dyslexia, a learning disability that interferes with the ability to decipher written language. At the time, in the early 1980s, IQ scores for children who were struggling to read needed to be above a certain level for experts to diagnose dyslexia. Other struggling readers often heard instead that they weren’t reading because they were lazy or stupid. Although plenty of scientific evidence has since debunked the idea that intelligence has anything to do with dyslexia, it remains one of many misconceptions about the disorder that have impeded progress in teaching children to read.

Today, studies suggest that as many as 20% of people in the United States have dyslexia, which accounts for up to 90% of learning disabilities ( Shaywitz, S. E., et al., Current Opinion in Psychiatry , Vol. 34, No. 2, 2021 ). Through studies of brains, genetics, and educational strategies, scientists are better understanding causes of reading troubles. But disagreement, debate, and misunderstandings rage on about many details, including how to define dyslexia, how to diagnose it, and how best to teach reading to struggling readers. These disagreements often incorporate politics as well as science.

Nevertheless, consensus is building that dyslexia impacts mental health, interventions can boost self-esteem, and there are clear ways of improving reading abilities for most people ( Georgiou, G. K., et al., Annals of Dyslexia , Vol. 74, No. 1, 2024 ).

“We’ve come a long way in trying to raise awareness and dispel the negative stereotype of dyslexia,” said Odegard, who is now a developmental cognitive psychologist and professor of psychology at Middle Tennessee State University and editor-in-chief of the journal Annals of Dyslexia. He learned the results of his third-grade IQ test after earning his PhD. “Although, that negative stereotype is still out there.”

Cascading consequences

In the context of tens of thousands of years of human history, reading and writing are extremely new technologies—emerging just a few thousand years ago and becoming available to much of society far more recently than that. Our brains did not evolve to handle the task of hearing individual speech sounds, and only a small percentage of children, maybe 5%, learn to read with very little support, said Daniel Willingham, PhD, a psychologist at the University of Virginia. Those students tend to have strong oral language skills and a good ability to distinguishing between sounds, such as the difference between “big” and “pig.”

How best to teach children to read has fueled decades of debate, often called the “reading wars.” That debate is particularly salient for children with dyslexia, which is in the Diagnostic and Statistical Manual of Mental Disorders (Fifth Edition) and generally considered to be a deficit in the ability to accurately and fluently decode, or turn printed words into speech. This disconnect essentially represents a bottleneck in the process of bridging the visual system and the language system, according to Kenneth Pugh, PhD, a cognitive neuroscientist at the Yale Child Study Center. “I always say if each word takes your entire soul to pull off the page,” he said, “then by the time you get to the end of the sentence, you kind of forgot the beginning.”

Studies indicate that dyslexia can have significant mental health consequences. Social anxiety, for one, was more prevalent in fifth-grade students who had literacy struggles in the second and third grades, compared with peers who didn’t have the same challenges early on, found a 2023 study of Greek children published in a special issue of the Annals of Dyslexia on dyslexia and mental health ( Kargiotidis, A., & Manolitsis, G., Annals of Dyslexia , Vol. 74, No. 1, 2024 ). Children with dyslexia who also had inattention or hyperactivity, which commonly co-occur, were particularly vulnerable to social anxiety, found another study in the same issue ( Annals of Dyslexia , Vol. 74, No. 1, 2024 ). Dyslexia has also been linked to depression and low self-esteem .

The disorder and its reverberations can affect the trajectory of a person’s life dramatically. Children with learning disabilities tend to lag behind in academic achievement, and social-emotional struggles can persist into adulthood ( Schwartz, A. E., et al., Journal of Policy Analysis and Management , Vol. 40, No. 2, 2021 ; Haft, S. L., et al., Journal of Learning Disabilities , Vol. 56, No. 3, 2023 ). Dyslexia is overrepresented in prisons, according to a report by the criminal justice research firm JFA Associates, and some 70% of inmates read at or below a fourth-grade level.

Stereotypes and stigma contribute to such negative outcomes, found a 2023 review of 16 studies that considered the psychological and academic outcomes for students with learning disabilities, including dyslexia. Stigma arises from the label that characterizes a person as “different,” the researchers wrote, which can play out in a variety of ways. Students might be physically separated from their peers during the school day. Teachers and parents might develop lower expectations of them, the researchers posited. And children might experience bullying from classmates while internalizing the belief that something is wrong with them. Overall, the review found that stigma contributes to low self-esteem in children with learning disabilities ( Haft, S. L., et al., Journal of Learning Disabilities , Vol. 56, No. 3, 2023 ).

Still, dyslexia often goes unidentified. In a sample of close to 10,000 fourth graders in Italy, nearly 2 out of 3 students with the disorder had not been diagnosed ( Barbiero, C., et al., PLOS ONE , Vol. 14, No. 1, 2019 ). Despite legislation in most U.S. states that governs screening, intervention, and other dyslexia-related services, non-White students and children who go to schools with predominantly non-White populations are also less likely than others to get diagnosed via dyslexia screening programs, Odegard and colleagues found in an analysis of data from 7,947 second-grade students in 126 schools in Arkansas ( Journal of Learning Disabilities , Vol. 53, No. 5, 2020 ). Students attending majority-White schools, on the other hand, had access to more reading supports than other schools, found research in Boston, according to an article in the Hechinger Report , an education publication.

Those disparities reflect and likely exacerbate gaps in reading ability, studies suggest. According to 2022 data from the National Assessment of Educational Progress (NAEP), just 33% of fourth-grade students and 31% of eighth-grade students are at or above proficiency levels in reading. Proficiency levels were 38% for White eighth graders compared with 16% for their Black classmates. Some of those children are likely to have dyslexia and other learning disorders and would benefit from extra intervention.

The interaction of reading troubles and self-esteem troubles can have cascading consequences beginning in elementary school, when struggles with reading begin to become highly visible, said Mark Seidenberg, PhD, a cognitive neuroscientist and professor of psychology who recently retired from the University of Wisconsin–Madison. Seidenberg has studied language, reading, and dyslexia for more than 40 years and has published dozens of peer-reviewed papers on the topic. Adults with dyslexia can learn to read, but issues with confidence can begin in childhood. “By the time they are in fourth to sixth grade, if they’re still failing, their motivation to continue drops off and they disengage,” Seidenberg said. “The consequences of not being able to read are huge.”

[ Related:   Treating patients with dyslexia ]

Understanding dyslexia

Diagnosing dyslexia early on is important because it can make the difference in whether or not a student qualifies for school-based educational services to improve reading, Pugh said. But diagnosis can be challenging because there is no definitive test that can determine whether someone does or does not have dyslexia. Like other forms of neurodiversity, the disorder occurs on a spectrum, and diagnoses usually involve screening assessments with cut-off points and a subjective evaluation by assessors who vary in their reliance on different models of the disorder.

Meanwhile, false stereotypes still get in the way of accurate diagnoses. The idea that people with dyslexia see letters backward, for example, is a myth that has persisted and proliferated, according to the Yale Center for Dyslexia and Creativity . What Odegard experienced as a child—the belief that there must be a significant difference between a child’s cognitive abilities and reading abilities in order to diagnose dyslexia—has also persisted even though the standard, known as the discrepancy model, has been debunked, Odegard said.

In the search for more objective measures, some researchers are looking to the brain, where studies using MRI and EEG are showing patterns that distinguish the brain of a person with dyslexia from the brain of a person without dyslexia. Scientists have long known that multiple brain areas are involved in reading. These regions, which regulate processes like speaking and object recognition, are predominantly in the left side of the brain, in areas such as the parietotemporal and occipitotemporal regions. In people with dyslexia, studies have indicated a smaller amount of gray matter and less brain activity in these regions . Dyslexic brains also show different patterns of activation in a variety of regions while reading compared with non-dyslexic brains ( Richlan, F., Frontiers in Psychology , Vol. 11, No. 155, 2020 ).

These patterns appear to be consistent across languages and writing systems, suggesting some universal signatures in the way the brain struggles to learn to read, Pugh said. (Although brain-imaging studies can’t yet be used for diagnosis, his group and others are looking into brain-stimulating techniques that might give specific neurons a kick, especially in children with dyslexia who struggle the most.) “If you’re typically developing, you develop a certain left hemisphere connection, particularly between the left occiptotemporal cortex and Wernicke’s and Broca’s [language areas]. They have to sort of strengthen each other and connect,” he said. “In the absence of treatment, dyslexia presents very often with a failure to see that.”

Genetics also plays a role in determining who develops dyslexia. Twin and family studies indicate that genes explain 40% to 60% of the risk for developing dyslexia ( Gialluisi, A., et al., Molecular Psychiatry , Vol. 26, No. 7, 2021 ). Multiple genes are involved, and studies are ongoing to understand the mechanisms and the ways that home and school environments influence the effect these genes have on the brain.

Richard Wagner’s group at Florida State University has proposed viewing dyslexia as a spectrum of severity and acknowledging that dyslexia has many causes that can interact with each other ( Journal of Learning Disabilities , Vol. 53, No. 5, 2020 ). “As opposed to thinking that there’s a dyslexia test or that there’s a single indicator, it’s a constellation of risk factors,” Odegard said, “some of them being your language skills, others being aspects around you.”

Overcoming reading struggles

Identifying who has dyslexia is only half the battle. Next comes the task of teaching these individuals to read. In general, studies indicate that for children with dyslexia, it is particularly important to address specific components of reading, Pugh said, including a focus on phonics, which makes the link between letters and sounds explicit.

In addition, the most successful instructional reading interventions include work on spelling, vocabulary, and connected-text reading (or reading multiple sentences that are related to each other), found a 2022 meta-analysis of 53 studies. And dose matters. For students with dyslexia or at risk for dyslexia, the study suggested that every extra hour of intervention helped improve outcomes ( Hall, C., et al., Reading Research Quarterly , Vol. 58, No. 2, 2023 ). Extra intensive and sustained instruction matters most for the 3% to 5% of children with dyslexia who struggle the most, Odegard added.

Managing stress and addressing mental health might be part of the solution, too, experts said, although research is still new and studies are small. Because anxiety is prevalent in children with learning disabilities and can interfere with learning, some experts advocate for strategies such as exercise, meditation, and mindfulness ( Tarrasch, R., et al., Frontiers in Psychology , Vol. 7, No. 578, 2016 ). Mentoring programs that connect children with similar struggles can also reduce depression and improve self-esteem, Stephanie Haft, a clinical psychology doctoral intern at the University of California, Berkeley, and colleagues found in an evaluation of a program that paired elementary and middle school students who have learning disabilities and attention-deficit/hyperactivity disorder with mentors in high school or college who have the same conditions ( Child and Adolescent Mental Health, Vol. 24, No. 4, 2019 ).

Instituting these approaches will require overcoming ingrained educational ideas, Seidenberg said. Instead of an explicit focus on phonics and other useful strategies, for instance, many schools continue to use curriculum known as “balanced literacy,” which is based on outdated ideas that children will learn to read if you hand them books and teach them to guess at what the words are based on letter and picture clues. It can be hard to persuade teachers to change when it seems that what they have been doing has worked for most students.

Researchers are also working to overcome a long history of skepticism about dyslexia. For decades, Seidenberg said, some influential educators argued that the disorder was simply an excuse made by ineffective teachers and that every child could learn to read if they were just taught correctly. As a result, dyslexia became a “dirty word” in education. Another persistent and harmful myth, he said, is the idea that dyslexia is an advantage or “desirable difficulty” that may produce extraordinary achievement ( Odegard, T. N., & Dye, M., Annals of Dyslexia , 2024 ). “We need neuro-realities ,” Odegard said, that don’t sugarcoat reality and instead “acknowledge what we really need as a community to help our children.” Knowing they have dyslexia can help children understand why they are having more trouble than their peers in school, and that can be heartening, Willingham added.

Given the obstacles to change, some advocates are pushing for policies that legislate evidence-based reading interventions. “You have generations of educators who’ve been taught that dyslexia was a thing that was invented by people to excuse the failures of the educational system,” Seidenberg said. “As opposed to, it’s a condition that actually affects people.”

Changing perceptions

As evidence accumulates about the most effective interventions, researchers are also gathering evidence about what makes some children resilient, even when they are at risk of dyslexia—with the hopes of boosting the same kind of resilience in others. Those factors can include social and emotional strengths and high-quality instruction early in life, wrote University of California, Los Angeles literacy researcher Maryann Wolf and colleagues in a 2023 review of the history and future of dyslexia ( Annals of Dyslexia , 2024 ).

On the cognitive side, Haft and a colleague wrote in a 2016 article for the International Dyslexia Association, it is important to nurture oral language skills, vocabulary knowledge, and goal-setting strategies. From a social-emotional perspective, it helps to give children with dyslexia a sense of control and self-worth (see Treating patients with dyslexia ).

Debate continues about whether dyslexia is associated with different ways of thinking or certain kinds of strengths. Based on anecdotal observations, people have long suggested that dyslexia is overrepresented among entrepreneurs and in creative fields. And a variety of pop culture books, including The Dyslexic Advantage , argue that understanding these differences can help people find workarounds, compensatory techniques, and useful technologies to succeed at school and in the workplace. “If you know who you are, you know how your mind works, you’ll know the best way to learn,” said coauthor Brock Eide in a lecture to The Lab School in Washington, D.C. “The key to success is building on your strengths.”

However, many of those theories remain speculative and based on correlations, Odegard said, and run the risk of causing harm through stereotyping. “The kids I work with tell me that these myths make them feel like impostors for not having one of these abilities or ways of thinking differently,” he said. For now, there are not enough data to say whether trends are real and biological, or if observations are based on “the fact that so many dyslexic kids have to fight like hell for everything, making some of them extra highly motivated,” Pugh said. “There are good reasons to explore this question further.”

Most studies on hypothetical strengths in dyslexia fail to acknowledge the heterogeneity of people with the learning disorder, Wolf added. “There needs to be far more and far better research on the putative strengths of individuals with dyslexia,” she said. In the meantime, students with dyslexia need to know that they are as talented and intelligent as their peers, wrote Wolf and colleagues in their 2024 paper arguing for a new definition of the disorder ( Annals of Dyslexia , 2024 ). As other studies have shown, there is no link between dyslexia and IQ, they pointed out ( Tanaka, H., et al., Psychological Science , Vol. 22, No. 11, 2011 ). As a difference, dyslexia becomes a disability only in the context of disabling environments. 

Despite the challenges that dyslexia presents for students, structured reading programs that emphasize resilience, persistence, and self-esteem can set children up for success, Wolf and colleagues concluded. “The history of rigorous reading intervention studies in the last twenty years underscores how well we can remediate children at risk for dyslexia, regardless of their race, socioeconomic background, or IQ,” they wrote. With early and effective interventions, they added, children can learn to read.

Further reading

Sold a story: How teaching kids to read went so wrong APM Reports, 2022

Supporting students with dyslexia National Center on Improving Literacy, 2024

Dyslexia Digital Library International Dyslexia Association

How to teach kids with dyslexia to read Miller, C., Child Mind Institute, 2024

Understanding dyslexia Martinelli, K., Child Mind Institute, 2023

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Designing for dyslexia: how architecture can address neurodiversity in k-12 schools.

Architects play a critical role in designing school environments that support students with learning differences, particularly dyslexia, by enhancing social and emotional competence and physical comfort. 

Beginning in the 2025-2026 school year, California will require dyslexia screening for all K-2 children as per the recent passage of Senate Bill 114 (Education Code 53008). This means all local education agencies will assess every pupil in grade K-2 for risk of reading difficulties. As a result, it’s anticipated that a meaningful number of additional students will be diagnosed with dyslexia and other learning differences soon.

Those who are diagnosed will greatly benefit from early identification, tailored curriculum and services at their school. Architects who design school environments can help in the ways we think about spaces for students who have learning differences. Applying key design principles to spaces not only improves the day-to-day experience for students with dyslexia– specifically in areas of social and emotional competence and their physical comfort in a space– but these strategies also help those within a classroom who may be considered neurotypical, including the faculty and administrators. In other words, designing for students with dyslexia has the power to benefit everyone.

Dyslexia, a lifelong learning difference, is a neurobiological disorder that affects how the brain processes information. The degree to which it impacts learning and developing varies. Most who are diagnosed have difficulty with phonological processing, including accurate word recognition and reading comprehension¹. As our educational system relies so much on reading and writing, it’s critical to think of all the ways students can gain confidence and comfort in a school setting, where some of their largest academic challenges can occur. 

Supporting Social and Emotional Competence in K-12 Schools

In addition to delivering their core curriculum, schools can take efforts to support students’ social and emotional competence (SEC) by bolstering confidence and resiliency². We see this happening in the built environment at three different scales: the campus level, the classroom level, and the individual level.  

Students with dyslexia are known for their creativity and three-dimensional thinking³. At the campus level, there should be spaces where students can excel in the arts and design-thinking. Providing well-equipped, large environments for music, art, performance spaces, and tinker labs can provide opportunities for learning and development giving students the chance to recognize their strengths outside of the core subjects and thus build self-esteem. 

At the classroom scale, confidence and resiliency can come with choice and appropriate tools organized and available for students to use without permission. At Winston Preparatory School , in Marin County, CA, their philosophy is to empower self-regulation and promote trying different solutions. In their classrooms students are given a sense of freedom and choice and this is supported by the classroom design. For example, a classroom with extensive flat countertops or shelves puts math manipulatives within arm’s reach, enabling students to select their preferred problem-solving tools such as blocks, empowered with how best they can learn.

A learning environment should also support students at the individual level of ergonomics and body movement. Students with learning differences can struggle with concentration and staying still. Instead of expecting students to sit in rows and concentrate, flexible furniture options and permission to stand or sit during class helps students manage their body at the back of the classroom without distracting others. Chairs with casters, wobble stools, standing desks, and even foam bench seating are all adaptable to movement and choice.  As Winston Prep Head of School Kristen Atkins noted, “We want to help students ask themselves ‘what do I need to do with my body right now?’ We encourage them to think about what might help them take a break cognitively, what will help them refocus? Whether that’s a certain type of chair, a walk outside, a drink of water. We give them options within limits but over time we get to simply say ‘you know what to do’.” Empowering students with options helps them build resiliency, and with resilience comes confidence to endure different types of experiences.

Improving Comfort for Students With Dyslexia  

In addition to building confidence, architects and designers should look for ways to promote comfort for dyslexic learners. As Sarah Fox, Director of Research at Charles Armstrong School in Belmont, Calif., has noted “Classrooms by design can be uncomfortable. Anything we can do to make the teachers more comfortable and students more comfortable means learning can happen.” We see opportunities for comfort at three scales: the campus level, the classroom level and the individual level.  

At the campus scale designers can make wayfinding and navigating to different buildings easier. Instead of relying on signs, we can signal a clear hierarchy of entry to a space with a taller pair of doors, a sculptural awning, or a special color. Designers can play to visual-spatial strengths by incorporating images, rather than written words. A connection to the outdoors with distinct, identifiable landscape features can be very valuable in helping students orient themselves around a campus.

At the classroom scale comfort comes from controlling light, temperature, and glare. Natural light is key. Atkins noted in her experience of moving from spaces with artificial light to natural daylight, she saw her students stop wearing baseball caps and stop asking for as much headache medicine. “It really was striking how natural daylight made such a difference, we reviewed the medical requests and we no longer were going through a Costco bottle of Tylenol every month.”  

Acoustics of mechanical fans and blowers is another important factor for classroom comfort. The importance was noted by Fox, “Room temperature should be regulated but done so quietly. Fans blow papers around and between that and the noise of heaters turning on and off it can be very distracting for students.” Installing radiant heating in the floor is an effective way to provide thermal comfort as air does not blow around a space.

At the individual scale classrooms with soft furniture choices, such as a beanbag chair provide a fairly standard comfortable seat. In addition to furniture, other tactile, sensory elements can help. For students with dyslexia who sometimes also are diagnosed with ADHD fidget toys and other diversion mechanisms can help the brain with the task at hand⁴. In every office at Winston Preparatory students can hold onto pillows with sequins that change patterns to provide a small place for movement without distraction. At the lobby area of Charles Armstrong School small ‘dimple pops’ are available for students to manipulate when meeting with administrators or waiting to be picked up. Offering small, hand-held ways to offer movement aids in comfort. 

As neuro-research evolves, the links between our built space, our bodies and our brains will continue to become more clear. As architects, we already know we are making design choices that impact students and faculty on a day-to-day basis which can deeply affect learning and thinking. For already diagnosed or newly diagnosed students with dyslexia and other learning differences, recognizing the power of space to build confidence and provide comfort is critical at different scales to optimize school environments.

About the Author Architect Sarah Knize , AIA, LEED AP, Associate Principal and K-12 Academic Practice Leader at Ratcliff , a San Francisco Bay Area-based healthcare and academic architecture firm known for creating inclusive environments that foster learning and community, designed a multi-year campus plan for Charles Armstrong School, a Grade 2-8 school serving dyslexic students in the Bay Area. 

¹ Shaywitz, Sally, MD and Jonathan Shaywitz, M.D. Overcoming Dyslexia: Second Edition, Knopf, 2020. ² Domitrovich, C., Syvertsen, A., and Calin, S. (2017) – Promoting Social and Emotional Learning in the Middle and High School Years. Penn State University ³ https://www.ribaj.com/intelligence/dyslexia-enhanced-ability-creativity-inventiveness ⁴ https://www.understood.org/en/articles/fidgets-for-kids-with-adhd

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Perspectives on dyslexia

Dyslexia, or a reading disability, occurs when an individual has significant difficulty with speed and accuracy of word decoding. Comprehension of text and spelling are also affected. The diagnosis of dyslexia involves the use of reading tests, but the continuum of reading performance means that any cutoff point is arbitrary. The IQ score does not play a role in the diagnosis of dyslexia. The cognitive difficulties of dyslexics include problems with speech perception, recognizing and manipulating the basic sounds in a language, language memory, and learning the sounds of letters. Dyslexia is a neurological condition with a genetic basis. There are abnormalities in the brains of dyslexic individuals. There are also differences in the electrophysiological and structural characteristics of the brains of dyslexics. Physicians play a particularly important role in recognizing children who are at risk for dyslexia and helping their parents obtain the proper assessment.

La dyslexie, une déficience de lecture, se produit lorsque l’individu éprouve d’énormes difficultés dans la vitesse et l’exactitude du décodage des mots. La compréhension de texte et l’épellation sont également touchées. Pour poser un diagnostic de dyslexie, il faut utiliser des tests de lecture, mais en raison de la séquence d’exécution de la lecture, toute limite d’inclusion est arbitraire. Le QI n’a rien à voir dans le diagnostic de dyslexie. Les troubles cognitifs des dyslexiques comprennent des troubles de perception du langage, de reconnaissance et de manipulation des sons fondamentaux d’une langue, de mémoire de la langue et d’apprentissage du son des lettres. La dyslexie est un trouble neurologique aux fondements génétiques. On remarque des anomalies dans le cerveau des dyslexiques, de même que des différences dans les caractéristiques électrophysiologiques et structurelles de leur cerveau. Les médecins jouent un rôle particulièrement important dans le dépistage des enfants vulnérables à la dyslexie et dans l’aide aux parents afin qu’ils obtiennent une évaluation convenable.

Dyslexia, also known as a reading disability, occurs when an individual has significant difficulty with speed and accuracy of word decoding. Comprehension of text is also affected. Dyslexia is usually accompanied by spelling difficulties. Dyslexia is stable, in that children identified as dyslexic are likely to continue to have reading difficulties throughout adolescence and adulthood ( 1 , 2 ).

DEFINITIONAL ISSUES

There are many complex issues to consider in developing an appropriate definition of dyslexia. One of the major problems is that there is no specific blood test or brain imaging result that can provide a diagnosis. Fundamentally, the issue is that reading is measured on a continuum and there is no cutoff score on a reading test that clearly divides individuals into dyslexic and nondyslexic groups. The distinction between dyslexia and normal reading is arbitrary; where the cutoff point is drawn varies from study to study.

Ellis ( 3 ) invokes a medical analogy when discussing dyslexia: “First, reading backwardness seems to be a graded thing more like obesity than measles. We cannot in any simple way divide the population into those who are dyslexic and those who are not, so it would seem unlikely that there will exist any symptom or sign that will quantitatively distinguish dyslexics from nondyslexics”.

In discussing the arbitrary nature of dyslexia, Shaywitz et al ( 4 ) noted: “Our findings indicate that dyslexia is not an all-or-nothing phenomenon, but like hypertension and obesity, occurs in varying degrees of severity. Although limitations on resources may necessitate the imposition of cutoff points for the provision of services, physicians must recognize that such cutoffs may have no biological validity”.

Exactly where the line is between dyslexic and nondyslexic is subjective and controversial. This relative uncertainty does not dispute the reality of dyslexia, but instead indicates that there is some subjectivity in the diagnosis.

Operationalizing the definition of dyslexia has proved to be contentious and difficult. First, there is the question of which reading test to use. It is now considered important to use a test of single isolated word reading, such as the Woodcock-Johnson Word Identification subtest or the Wide Range Achievement Test. In both of these tests, the individual is required to read words that increase in difficulty (eg, from simple words to complex multisyllable words, such as ‘cat’, ‘emphasis’ and ‘idiosyncrasy’). Test scores are compared with scores from other individuals of the same age level.

An important test for dyslexia is a test of pseudoword reading (eg, the Woodcock Word Attack test). This test involves the reading of pronounceable combinations of letters that do not represent English words but can be articulated using the pronunciation rules of English. Examples include items such as ‘bab’, ‘shum’, ‘cigbet’ and ‘bafmotbem’. This is a test of basic decoding skills. Having these decoding skills is especially important when learning to read and to be able to ascertain the pronunciation of new words that have never been encountered before.

The discrepancy definition

Until recently, the typical definition of dyslexia involved a discrepancy between an IQ score and a reading score. If the IQ score was found to be significantly higher than the reading score, then this discrepancy was used as an index of dyslexia. This definition has been discredited for a variety of reasons. A detailed discussion on this topic can be found elsewhere ( 5 ). The IQ test measures vocabulary, verbal memory and specific knowledge, and these are skills that may be deficient in the dyslexic. Therefore, the IQ score may be an inadequate measure of the so-called intellectual potential of a dyslexic. In addition, a number of studies ( 6 – 9 ) in different countries have found that there are no differences in children who have reading problems between those who have a discrepancy between IQ and reading scores and those who do not. These findings suggest that a discrepancy between IQ and reading scores is not necessary to indicate dyslexia, and that a low score on a reading test is, in fact, an indication of a reading problem. There is evidence to suggest that a child’s IQ score does not predict his or her ability to benefit from remediation ( 10 , 11 ).

Another issue is which cutoff score to use to diagnose dyslexia. Basically, reading scores are a continuous distribution. At some point in the reading, the delay becomes so severe (compared with other individuals of the same age and educational background) that we call it dyslexia.

Although reading comprehension is important and is the major purpose for reading, dyslexia is best recognized by difficulties at the word level. Decoding words is critical for developing comprehension skills. Reading comprehension is usually tested by having the individual read a passage and answer questions about the passage. Reading comprehension tests are usually timed. There are some individuals who, although they can read words, have difficulty with reading comprehension because they may lack the inferential skills to make sense of what they read, or because they may read slowly. They may not have sufficient background knowledge to understand the text or the questions. Lesaux et al ( 12 ) found that giving dyslexics extra time on a reading comprehension test improved their reading scores.

Estimates of prevalence depend on the particular definition of dyslexia used in the study ( 13 , 14 ). Depending on the definition used, 5% to 10% of the population is considered to have dyslexia; however, because of the nature of the definitional issues (as described above), an estimate of prevalence is specific to a particular sample and to the definition used in a study.

Dyslexia was first described in the scientific literature by several physicians, who noted cases of individuals with apparently normal intelligence who could not learn to read ( 15 ). These cases were called word blindness. One of the pioneers in the field of dyslexia was Orton ( 16 ), who believed that the problem in dyslexia was one of visual perception and visual memory.

In the years that followed, various theories, including hypotheses about motor difficulties and perceptual problems as the basis of dyslexia, were advanced. The belief was that dyslexia was a perceptual problem, stemming from the idea of word blindness. It was also a common belief, and probably a belief held by many today, that the defining symptom for dyslexia was writing letters and words backwards. This conceptualization of dyslexia as a visual problem and as the primary symptom being the writing of letters and words backwards has been discredited by studies, including those by Liberman et al ( 17 ) and Vellutino ( 18 ).

TWO ROUTES TO READING

Scientists have used theories about reading to help understand dyslexia. One of the most widely accepted theories of reading is called the dual route theory ( 19 ). In this theory, there are two mechanisms that individuals use to read words: the direct (orthographic) route and the indirect (phonological) route. The direct route involves looking at a word and automatically knowing what it says. For frequently used words and words that have been seen before, this route is probably the one that is used. Skilled readers use this route for most of what they read, although they can use another route when they encounter words that are either new or relatively unfamiliar. The indirect route involves translating the letters into sounds and knowing the pronunciation of words from the combination of sounds. The use of this route involves what is called phonological processing. This route is commonly used at the beginning of the development of reading skills in which words are carefully sounded out and in more advanced readers when they encounter new words. Most dyslexics have a great deal of difficulty with this route because they lack phonological skills.

COGNITIVE ASPECTS OF DYSLEXIA

A breakthrough in the understanding of dyslexia occurred approximately 35 years ago, when a picture of the major cognitive difficulties in dyslexia began to emerge more clearly ( 20 ). Liberman and colleagues ( 20 – 22 ) recognized the importance of speech and language as the basis for reading, and that children must map the written word on to the spoken word when learning to read. It was assumed in the past that visual difficulties or problems with hand-eye coordination served as the basis for dyslexia. It is now clear that the major problem with dyslexia involves difficulties with phonological processing, that is, being able to segment words into their component sounds, and associate letters with their sounds and phonological awareness (ie, the ability to segment speech into small parts, such as syllables, and the smallest units of sound, phonemes). As young children, dyslexics have difficulties with tasks such as discriminating the individual sounds in words (eg, what does ‘pink’ with out the ‘p’ say?), recognizing words that rhyme (eg, which of the following words rhymes with cat: sun, hat or star) or recognizing whether ‘cat’ and ‘kite’ start with the same sound ( 20 , 23 ). Studies such as those by Lundberg et al ( 24 ) and Elbro and Petersen ( 25 ) have shown that children who receive training in these phonological awareness skills demonstrate improved reading abilities.

One aspect of this phonological deficit is that dyslexics show subtle difficulties in speech perception at the level of the phoneme. Studies such as those by Godfrey et al ( 26 ), Manis et al ( 27 ), Reed ( 28 ) and Werker and Tees ( 29 ) have shown that dyslexics perform poorer than nondyslexics on measures of speech perception. For example, Bertucci et al ( 30 ) found that the perception and production of vowels were particularly difficult for dyslexics. The speech processing difficulties for dyslexics include weak phonological coding for vowel sounds with similar phonetic characteristics.

Mody et al ( 31 ) found differences between some dyslexics and nondyslexics with respect to the discrimination of sounds such as ‘ba’ and ‘da’. Only some dyslexics have this problem. As methods of speech and sound science advance, it may eventually be found that this speech perception problem is one of the fundamental difficulties of the dyslexic.

When dyslexics are learning to read, they have trouble learning the sounds of letters and the spelling of words. Later on, although they can read words, their reading may be slow, and many have difficulty remembering what they have read. Stanovich ( 32 ) provided evidence for what he called the ‘Matthew effect’ (based on the writings of Matthew in the Bible that the rich get richer and the poor get poorer). Stanovich ( 32 ) states that “individuals who have advantageous early educational experiences are able to utilize new educational experiences more efficiently”. In contrast, children who have reading difficulties read less and do not acquire the vocabulary and concepts that they need and, thus, fall further behind in their reading and academic skills.

GENETIC AND NEUROLOGICAL BASIS

Dyslexia has a genetic basis, and it is clear that dyslexia tends to run in families ( Table 1 ). Research has identified several chromosomes that appear to contain the gene or genes for dyslexia, although the exact genetic mechanisms and the inheritance patterns are not known. Familial studies ( 33 – 39 ) and discoveries regarding the involvement of specific chromosomes ( 40 – 42 ) clearly indicate the genetic basis of dyslexia. Chromosomes 6 and 15 have been implicated. Obviously, environmental factors play a role, but the role of genetics is quite strong ( 43 ). A study by Castles et al ( 43 ) found that phonological dyslexia (in which individuals have more trouble reading pseudowords) was more heritable than orthographic dyslexia (in which individuals have more trouble reading exception words), although both types showed a significant heritability.

Risk factors for dyslexia

There is clearly a neurological basis for dyslexia. A number of postmortem studies have indicated abnormalities in the brains of dyslexic individuals ( 44 , 45 ). The universal finding is an absence of the usual asymmetry in the planum temporale. There may also be structural differences between dyslexics and nondyslexics in the corpus callosum, which controls the communication between the two hemispheres of the brain ( 46 , 47 ).

A number of electrophysiological studies have shown differences between dyslexics and nondyslexics. Event-related potentials may be used to measure the timing and the brain areas used during the cognitive processing of print and language. For example, a number of studies ( 48 – 50 ) have found that the event-related potentials of dyslexics, in contrast with nondyslexics, failed to show what is called mismatched negativity, which is a negative deflection in the wave in response to a change in the stimulus.

Functional magnetic resonance imaging has shown that there are structural differences in the brains of dyslexics and nondyslexics. The exact nature of these differences varies from study to study. In general, differences in the planum temporale have been found such that asymmetries are great in the nondyslexic, and the direction may even be reversed in the dyslexic ( 51 , 52 ). Casanova et al ( 53 ) found abnormalities in the left hemisphere of dyslexic individuals; specifically, the following structures were involved: extrapyramidal and limbic systems, amygdala, hippocampus, parahippocampal gyrus, putamen and globus pallidus.

Although it is a common belief that men are significantly more likely to be dyslexic than women, this assumed sex imbalance is not substantiated by recent research ( 54 , 55 ). There may be slightly more men than women who have dyslexia, but the difference is not significant. This notion is illustrated by a study ( 56 ) of an epidemiological sample of children in grades 2 and 3 in which reading and IQ tests were used to provide a psychometric definition of dyslexia. The investigators found that 8.7% of the boys and 6.9% of the girls were dyslexic in grade 2, and that 9.0% of the boys and 6.0% of the girls were dyslexic in grade 3. However, when they examined the sex differences in referral rates in the dyslexics identified by the teachers, they found that 13.6% of the boys and 3.2% of the girls were identified as dyslexic in the second grade, and that 10.0% of the boys and 4.2% girls were identified as dyslexic in the third grade, indicating a significant referral bias in favour of boys. Although the actual incidence of dyslexia was similar in boys and girls, boys were much more likely to be referred for possible assessment. In general, Shaywitz et al ( 56 ) found that the boys were identified because of behavioural difficulties in the classroom, which drew the teacher’s attention to them. The girls were much less likely to have behaviour problems and, thus, were not identified as having reading difficulties, although they were almost as likely as boys to have a disability.

ASSESSMENT OF DYSLEXIA

Any individual (child or adult) in whom a reading problem is suspected should receive an assessment. This assessment is available in schools and in institutions of higher education. The assessment should involve a thorough measurement of reading, spelling and arithmetic skills. An intelligence test or IQ score is not necessary, as demonstrated by the latest research in the area; however, despite the literature, some jurisdictions still require an IQ test. This state of affairs is unfortunate because there is either a long wait time for testing – sometimes as long as one to two years in many school districts – or parents or individuals must go to a private psychologist to receive the testing, which is quite expensive and out of the financial reach of many individuals. However, third party insurers may cover the cost in some instances.

CROSS-LINGUISTIC STUDIES

Dyslexia has the same manifestation in all alphabetic languages that have been studied and in languages that are nonalphabetical, such as Chinese and Japanese. The primary deficit is phonological (even in Chinese), although problems with visual memory, short-term verbal memory and syntax exist in dyslexia in all languages ( 57 ).

EDUCATIONAL INTERVENTIONS

There are a number of educational interventions that can be useful in helping the dyslexic individual. Some of these are direct treatments, while others involve providing accommodations to the learning environment.

Accommodations

Educational accommodations include the use of computers, tape recorders, screen readers and speech recognition devices. Many dyslexics have illegible handwriting. The computer can be especially useful, particularly if touch typing skills are learned. Computers also have spell checking programs, which are particularly useful because dyslexics have poor spelling. Tape recorders can be useful for the child to record his or her ideas, which can then be transcribed later. Tape recorders can also be useful in classes and lectures because note taking skills can be a problem for dyslexic individuals. Screen readers are devices that read aloud what is on the computer screen and can be very helpful for dyslexics. Books on tape can also be helpful. Speech recognition devices and programs are especially useful; the individual can talk into a microphone and see his or her words appear on the screen.

In some cases of dyslexia, the direct and systematic teaching of letters and their corresponding sounds (ie, phonological skills) is an important way to help dyslexics. Programs such as those described by Hatcher ( 58 ) and Nicolson et al ( 59 ) systematically teach individuals the sounds of the letters and have been found to be successful.

Vaughn et al ( 60 ) found that programs designed to enhance reading fluency or reading strategies resulted in improved reading for children with reading difficulties.

Lovett et al ( 61 – 64 ) and Vellutino and Scanlon ( 65 ) used a detailed program that involved training in word recognition and decoding skills to improve the reading skills of dyslexic children.

Computerized programs have been helpful in some cases. In one study, Wise et al ( 66 ) used computers to help dyslexic children. Children read books on computers that were linked to speech synthesizers and then obtained feedback on words that were difficult for them. As a result of this system, the children’s attitudes toward reading improved. Irausquin et al ( 67 ) showed that computerized exercises that train speed or automatization are helpful in improving the reading of dyslexic individuals. Lovett et al ( 68 , 69 ) used a computer speech-based program to train reading skills in dyslexic children.

It is also important to discover the talents of dyslexics. Many dyslexics are gifted in sports, art, music or dance ( 70 ), while others have superior visuospatial skills. These skills can be useful in careers such as architecture or engineering.

COMORBIDITY

Dyslexia frequently occurs with other conditions, such as an arithmetic learning disability, attention deficit disorder, attention deficit hyperactivity disorder, obsessive-compulsive disorder and Tourette’s syndrome ( 71 ). Reading and language disorders may be associated with behavioural difficulties, but it is likely in many cases that the behavioural difficulties are a consequence of the reading difficulty and not a cause of it ( 72 ). It is particularly important that physicians do not ignore the possibility of dyslexia when other developmental disorders are present.

IMMIGRANT CHILDREN AND DYSLEXIA

Canada is a multicultural, multiethnic nation. Especially in the larger cities, there are significant numbers of children who are being educated in school in a language other than their native tongue. There has been some research conducted on children learning English as a second language, but very little research on immigrant children learning French as a second language. In general, these studies found that if immigrant children enter school in the first few grades and receive good instruction, they can catch up to their nonimmigrant peers ( 73 , 74 ). What is important to know is that children who are still having significant difficulties after a few months or a year of instruction in English may be dyslexic. Often, these children are ignored and the problem is assumed to be due to the fact that their first language is not English. In reality, children who struggle in school, even if their first language is not English, should be screened and assessed to determine whether they are dyslexic. Considering the significant dropout rate of children whose first language is not English, it is very important to investigate the possibility of dyslexia.

DYSLEXIA AND PREMATURITY

Very low birth weight children, that is, children whose birth weights are lower than 1500 g, are at significant risk for dyslexia and other learning disorders ( 8 , 75 , 76 ) ( Table 1 ). Unfortunately, these children are less likely to be identified because their difficulties are less likely to be recognized.

SIGNS OF DYSLEXIA

Delayed language development may indicate that a child is at risk for dyslexia. Children who show delayed language development at three and four years of age are at risk for dyslexia, although many children who eventually become dyslexic have perfectly normal language development. Studies ( 77 , 78 ) have shown that early language difficulties and a diagnosis of language impairment in childhood is predictive of reading disabilities in the later school years and during adolescence and adulthood. Although not all children who have language disorders in early childhood become dyslexic, it is a very important indicator of a possible problem; these children should be monitored very carefully.

Academic difficulties in school, especially difficulty with learning how to read, are a sign of dyslexia. Although children learn to read at different rates, if a child is having difficulty and performing significantly below his or her peers after a few months of reading instruction, this delay is a sign of a potential problem and should not be ignored.

School phobia and/or somatic complaints that appear on school days, especially on Monday, are a sign of a possible learning disability ( Table 2 ). Prompt treatment and investigation of a possible reading problem or other learning difficulty is critical.

Signs of dyslexia

Children at risk for reading difficulties can be identified in kindergarten (five years of age) and intervention programs can be provided. In one study, Lesaux and Siegel ( 74 ) found that children identified as at-risk for reading difficulties in kindergarten, regardless of whether their first language was English, benefited from classroom-based intervention programs that emphasized phonological awareness, vocabulary and reading strategies.

CURRENT DIRECTIONS IN DYSLEXIA

Recently, an alternative to the labelling of individuals as dyslexic to make them eligible for special education services has been proposed. The model is called Response to Instruction and it involves the early identification of children with difficulties, providing a classroom based-intervention and then providing more individualized academic intervention for children who still continue to have difficulties. This model holds promise for the prevention, or at the very least the reduction, of serious reading problems. It is considerably less costly than a model that requires extensive testing and waiting until the child is failing before help is considered.

CONCLUSIONS

It is important to recognize that behavioural difficulties in school may be a sign of dyslexia. Any sign of problems in learning to read, even very early in a child’s school career, should be taken seriously and investigated. The common assumption that the child will grow out of the problem is not a valid one in most cases. We know that early identification and early intervention can prevent most serious reading difficulties, or at least reduce the severity of them. Any school difficulties or behavioural problems should be investigated immediately. School phobia and/or somatic complaints that appear on school days are a sign of a possible learning disability.

Physicians have an important role to play in the identification of children at risk for dyslexia. In addition to recognizing the signs of possible dyslexia, physicians or their office staff may be able to conduct some brief screening tests, including some standardized tests of reading, spelling and arithmetic ( Table 3 ).

Screening tools

There is evidence that significant numbers of dyslexics are represented in populations of runaway homeless street youths ( 79 ), adolescent suicide victims ( 80 ) and juvenile offenders ( 81 ). It is important that we recognize these difficulties early and make an attempt to eliminate them or reduce their severity.

Physicians have a particularly important role in recognizing a child who is at risk for dyslexia and helping the parents obtain the proper assessment.