Dyslexia Research Research Articles

Subtypes of Dyslexia and the Current Status of Morphemic Awareness Interventions

This paper summarizes and analyses the subtypes of dyslexia, and finds that the major frameworks for dyslexia research, both in alphabetic writing system and Chinese, include three areas of delineation based on reading model theory, basic perceptual deficits, and cognitive-linguistic deficits. Then describes how morphemic awareness is measured, and the current state of research on morphemic awareness interventions for dyslexia was reviewed, and it was found that morphemic awareness instructional interventions are better, and the content of the interventions varies across researchers and subjects. Future interventions for children with dyslexia may consider the use of targeted instructional interventions for morphemic awareness.

The Roles of Rule Type and Word Term in the Deductive Reasoning of Adults with and without Dyslexia.

Despite its importance to everyday functioning, reasoning is underexplored in developmental dyslexia. The current study investigated verbal deductive reasoning on the Wason selection task, not previously used in dyslexia research despite its well-established pedigree. Reasoning rule was manipulated, with the conditional rules varying in the logical values presented. The word frequency and imageability of the word terms was also manipulated. Twenty-six adults with dyslexia and 31 adults without dyslexia completed Wason selection task problems. No group difference in reasoning accuracy or completion time was found. However, the participants were most accurate when reasoning with the rule type "If p, then not q" and least accurate with the rule type "If p then q". More trials were also answered correctly when the word terms were highly imageable but of average word frequency. These findings are in line with the general reasoning literature. Dyslexia status did not interact with either rule type or word term type. The study expands upon previous research by testing verbal deductive reasoning in dyslexia, highlighting the role of imageability in facilitating reasoning performance for all, regardless of the presence or absence of dyslexia. Implications for the design of educational materials are considered.

The Challenges Involved in Teaching Biblical Hebrew to Students With Dyslexia: Some Observations

ABSTRACTStudying Biblical Hebrew is increasingly considered a viable option for students with dyslexia. This presents particular challenges not just for the students but also for their teachers, because the pedagogical methods for teaching ancient languages have traditionally depended on strategies that create difficulties for dyslexic students. This paper outlines the particular challenges of Biblical Hebrew for teachers of students with dyslexia and makes some proposals for addressing those challenges. Responding to dyslexia research, this paper considers the effects of phonological, morphological, and other deficits; outlines teaching and assessment strategies; and argues that learning Biblical Hebrew can be a transformative experience for students with specific learning difficulties.

Association of exposure to phthalates and phthalate alternatives with dyslexia in Chinese primary school children.

Previous studies have shown associations between children's exposure to phthalates and neurodevelopmental disorders. Whereas the impact of exposure to phthalate alternatives is understudied. This study aimed to evaluate the association of exposure to phthalates/their alternatives with the risk of dyslexia. We recruited 745 children (355 dyslexia and 390 non-dyslexia) via the Tongji Reading Environment and Dyslexia Research Project, and their urine samples were collected. A total of 26 metabolites of phthalates/their alternatives were measured. Multivariate logistic regression and quantile-based g-computation were used to estimate the associations of exposure to the phthalates/their alternatives with dyslexia. More than 80% of the children had 17 related metabolites detected in their urine samples. After adjustment, the association between mono-2-(propyl-6-hydroxy-heptyl) phthalate (OH-MPHP) with the risk of dyslexia was observed. Compared with the lowest quartile of OH-MPHP levels, the odds of dyslexia for the third quartile was 1.93 (95% CI 1.06, 3.57). Regarding mixture analyses, it was found that OH-MPHP contributed the most to the association. Further analyses stratified by sex revealed that this association was only observed in boys. Our results suggested a significantly adverse association of di-2-propylheptyl phthalate exposure with children's language abilities. It highlights the necessity to prioritize the protection of children's neurodevelopment by minimizing their exposure to endocrine-disrupting chemicals like di-2-propylheptyl phthalate.

Sensory temporal sampling in time: an integrated model of the TSF and neural noise hypothesis as an etiological pathway for dyslexia.

Much progress has been made in research on the causal mechanisms of developmental dyslexia. In recent years, the "temporal sampling" account of dyslexia has evolved considerably, with contributions from neurogenetics and novel imaging methods resulting in a much more complex etiological view of the disorder. The original temporal sampling framework implicates disrupted neural entrainment to speech as a causal factor for atypical phonological representations. Yet, empirical findings have not provided clear evidence of a low-level etiology for this endophenotype. In contrast, the neural noise hypothesis presents a theoretical view of the manifestation of dyslexia from the level of genes to behavior. However, its relative novelty (published in 2017) means that empirical research focused on specific predictions is sparse. The current paper reviews dyslexia research using a dual framework from the temporal sampling and neural noise hypotheses and discusses the complementary nature of these two views of dyslexia. We present an argument for an integrated model of sensory temporal sampling as an etiological pathway for dyslexia. Finally, we conclude with a brief discussion of outstanding questions.

Overview of Research on Dyslexia Assessment and Identification in China

Dyslexia can affect students’ academic performance, self-esteem, mental health, social and emotional development, career and life prospects. Currently, there is a lack of scientifically unified methods and tools for dyslexia assessment and identification in China, resulting in a lower incidence rate of Chinese dyslexic students being discovered. Scientifically and accurately assessing and identifying dyslexic students and providing them with corresponding support and intervention measures are key issues in dyslexia research. This paper aims to analyze the progress of research on dyslexia assessment and identification in China, evaluate its current status, and summarize inspirations for dyslexia assessment and identification for future reference.

Genetic Modifications of Developmental Dyslexia and Its Representation Using In Vivo, In Vitro Model.

Dyslexia is a genetic and heritable disorder that has yet to discover the treatment of it, especially at the molecular and drug intervention levels. This review provides an overview of the current findings on the environmental and genetic factors involved in developmental dyslexia. The latest techniques used in diagnosing the disease and macromolecular factors findings may contribute to a higher degree of development in detangling the proper management and treatment for dyslexic individuals. Furthermore, this review tried to put together all the models used in the current dyslexia research for references in future studies that include animal models as well as in vitro models and how the previous research has provided consistent data across many years and regions. Thus, we suggest furthering the studies using an organoid model based on the existing gene polymorphism, pathways, and neuronal function input.

Understanding the interplay between executive functions and reading development: A challenge for researchers and practitioners alike.

In June of 2022, The Dyslexia Foundation (TDF) organized a convening of dyslexia researchers and practitioners around the topic of executive functions. There was consensus on the importance of executive functions for reading development. However, the difficulty of defining, measuring, and training executive functions emerged as a challenge for researchers and practitioners alike. This special issue presents a collection of articles that survey different perspectives, define the current knowledge base, highlight challenges and inconsistencies in research, and chart a path towards a more nuanced understanding of the role of executive functions in reading and dyslexia.

Recent Advances in Chinese Developmental Dyslexia

Chinese developmental dyslexia (DD) research provides important insights into the language-universal and language-specific mechanisms underlying dyslexia. In this article, we review recent advances in Chinese DD. Converging behavioral evidence suggests that, while phonological and rapid automatized naming deficits are language universal, orthographic and morphological deficits are specific to the linguistic properties of Chinese. At the neural level, hypoactivation in the left superior temporal/inferior frontal regions in dyslexic children across Chinese and alphabetic languages may indicate a shared phonological processing deficit, whereas hyperactivation in the right inferior occipital/middle temporal regions and atypical activation in the left frontal areas in Chinese dyslexic children may indicate a language-specific compensatory strategy for impaired visual-spatial analysis and a morphological deficit in Chinese DD, respectively. The findings call for further theoretical endeavors to understand the language-universal and Chinese-specific neurobiological mechanisms underlying dyslexia and to design more effective and efficient intervention programs.

Trends in Dyslexia Research during the Period 1950 to 2020-Theories, Definitions, and Publications.

Introduction. The focus of the present paper is on (1) how dyslexia research and hence definitions have developed during the period 1950–2020 and includes (2) a database search of scientific publications on dyslexia during the same period. The focus is on the definitions of dyslexia and the organization of the network search based on the causal four-level model by Morton and Frith. Method. (1) The definitions are presented in accordance with a historic review of dyslexia research from 1950 to 2020 and based on (2) Google Scholar counts of publications on dyslexia, on defining dyslexia, on dyslexia at the four levels (symptomatic, cognitive, biological, environmental), and by areas (sensorimotor, comorbidity). Finally, a percentage calculation shows the relative development within each level and area by decennium (1950–1960, 1960–1970, 1970–1980, 1990–2000, 2002–2010, 2010–2020). Results. (1) Of the seven definitions presented, only the definition by the BDA 2007 included the four levels of the causal model. (2) The number of publications increased substantially over the period. However, relatively few publications have defined dyslexia. An increase in publications from 1950 to 2020 was seen across the four levels and two areas—however, with an alteration in the thematic focus over this time span. Summary. Defining dyslexia has still not reached a consensus. This uncertainty may explain why only one of the seven definitions proved satisfactory according to the four-level model. Along with the general increase in research, publications on dyslexia have increased accordingly during the period 1950 to 2020. Although the symptomatic level has played a dominant role over the whole period, thematic shifts have been seen over these 70 years. In particular, a substantial thematic shift was seen by the turn of the millennium. There has been a relative increase in the focus on literacy at the symptomatic level, on phonological awareness at the cognitive level, in gender at the biological level, and second language learning as comorbidities. However, increases in counts are not alone a valid indication of scientific progress. In particular, the lack of definitional criteria as a basis for participant and method selection should attract much more focus in future studies. The present study underlines the multifactorial nature of dyslexia, as evidenced by a substantial increase in the number of publications on the subject. It is a challenge for future research to continuously use and possibly redefine dyslexia definitions in line with such standards.

Continuing the Debate: A Response to the Literacy Research Association’s Dyslexia Research Report

The Literacy Research Association (LRA) is known for releasing research reports on essential topics in the field of literacy. An Examination of Dyslexia Research and Instruction, with Policy Implications is a recent LRA report with far-reaching impact in education and policy. The report claimed to be a summary of dyslexia research and instruction, however, much recent research on dyslexia definitions, diagnosis, interventions, neuroscience, and law was left out. This paper is a response to the LRA report with the intent to examine elements of the report that are particularly important and well explained, as well as those that are problematic.

Educational Insights into Dyslexia

Dyslexia is a specific learning disorder characterized by difficulties in reading, writing, and spelling due to compromised phonological processing skills. Treatment of dyslexia solely with medical support is far-fetched. However, it can be surmounted by the combination of special education interventions and supportive psychosocial care. Suitable approaches coupled with beneficial learning strategies enable dyslexic learners with consummate linguistic achievement. Although dyslexia research offers an increased understanding from a biological standpoint, the knowledge gap on the educational front is unfortunately persistent. To this end, this paper revisits the teaching-learning aspects of dyslexia. Teaching principles and approaches, strategies to support learning, and personalized educational plans are discussed in detail. Acknowledging the difficulty, familiarizing with the approaches, and attaining successful outcomes via essential practices emphasize the inclusiveness of dyslexic learners in the curriculum. We contend that the educational insights into dyslexia will provide informed teaching and learning solutions.

Association between urinary dialkylphosphate metabolites and dyslexia among children from three cities of China: The READ program

Exposure to organophosphate (OP) insecticides has been found to be related to neurodevelopmental disorders in children. However, no study has examined the association between OP insecticide exposure and the risk of dyslexia among children. We aimed to explore the association between OP insecticide exposure, indicated by urinary dialkylphosphate metabolites (DAPs), and the risk of dyslexia among Chinese Han children from three cities. A total of 845 children (422 dyslexics and 423 non-dyslexics) from Tongji Reading Environment and Dyslexia research program were included in the current case-control study. We measured six DAPs in urine samples, collected from November 2017 to December 2020. Logistic regression models were used to estimate odds ratios (ORs) for the association between DAPs and dyslexia risk, adjusting for potential confounders. The detection frequencies of DAPs were above 97.5%, except for diethyldithiophosphate and dimethyldithiophosphate. Diethyl phosphate metabolites (DEs) were significantly associated with the risk of dyslexia. Compared with the lowest quartile, the adjusted ORs of dyslexia risk for the highest quartile of urinary diethylthiophosphate (DETP) and diethylphosphate (DEP) were 1.82 (1.04, 3.20) and 1.85 (1.08, 3.17), respectively. In addition, the adjusted ORs for dyslexia per 10-fold of urinary DEP, DETP, and ∑DEs concentration were 1.87 (1.12, 3.13), 1.55 (1.03, 2.35), and 1.91 (1.13, 3.21), respectively. Analyses stratified by gender indicated that such associations were more significant among boys. This study suggested that exposure to OP insecticides may be related to dyslexia among Chinese Han children from the three studied cities. However, our results should be interpreted with caution because of the case-control design and the fact that only one-spot urine sample was collected from the children. More studies with children living in China are necessary concerning the relatively high levels of urinary OP metabolites in our study.

Common Misconceptions about the Phonological Deficit Theory of Dyslexia.

In this discussion paper, I review a number of common misconceptions about the phonological deficit theory (PDH) of dyslexia. These include the common but mistaken idea that the PDH is simply about phonemic awareness (PA), and, consequently, is a circular “pseudo”-explanation or epiphenomenon of reading difficulties. I argue that PA is only the “tip of the phonological iceberg” and that “deeper” spoken-language phonological impairments among dyslexics appear well before the onset of reading and even at birth. Furthermore, not even reading-specific expressions of phonological deficits—PA or pseudoword naming, can be considered circular if we clearly distinguish between reading proper—real meaning-bearing words, or real text, and the mechanisms (subskills) of reading development (such as phonological recoding). I also explain why an understanding of what constitutes an efficient writing system explains why phonology is necessarily a major source of variability in reading ability and hence a core deficit (or at least one core deficit) among struggling readers whether dyslexic or non-dyslexic. I also address the misguided notion that the PDH has now fallen out of favor because most dyslexia researchers have (largely) ceased studying phonological processing. I emphasize that acceptance of the PDH does not imply repudiation of other non-phonological hypotheses because the PDH does not claim to account for all the variance in reading ability/disability. Finally, I ask where neurobiology enters the picture and suggest that researchers need to exercise more caution in drawing their conclusions.

An Examination of Dyslexia Research and Instruction With Policy Implications

An Examination of Dyslexia Research and Instruction With Policy Implications

Examining the Scientific Productivity of Authors in Dyslexia Research: A Study Using Lotka's Law

Examining the Scientific Productivity of Authors in Dyslexia Research: A Study Using Lotka's Law

A Pioneer in Context: T R Miles and the Bangor Dyslexia Unit

ABSTRACT T R (‘Tim’) Miles (1923–2008) was one of the most important pioneers of dyslexia research and treatment in the UK. He worked with dyslexics from the time of his appointment to a lectureship at Bangor in 1949 and later, with his wife, established the Dyslexia Centre there. Miles’ professional role and theoretical contribution are reasonably well documented, not least through his own autobiographical account of them. I aim to reappraise his work in the field, against a wider set of circumstances. Tim was a great all-rounder: a noted sportsman and musician, and a committed Quaker who published books on the philosophy of religion and its experiential claims. Moreover, he operated in a Welsh environment which needs explication, one where bilingualism became increasingly a matter of public debate and contestation: an issue of obvious relevance to the study of dyslexia. Miles, who famously expanded the scope of our understanding and definition of ‘dyslexia’, himself deserves a broader appreciation.

Reintroducing Dyslexia: Early Identification and Implications for Pediatric Practice.

Dyslexia is a common learning disorder that renders children susceptible to poor health outcomes and many elements of socioeconomic difficulty. It is commonly undiagnosed until a child has repeatedly failed to learn to read in elementary school; this late diagnosis not only places the child at an academic disadvantage but also can be a precursor to psychiatric comorbidities such as anxiety and depression. Genetic and neuroimaging research have revealed that dyslexia is heritable and that it is undergirded by brain differences that are present even before reading instruction begins. Cognitive-behavioral research has revealed that there are early literacy skill deficits that represent red flags for dyslexia risk and can be measured at a preschool age. Altogether, this evidence points to dyslexia as a disorder that can be flagged by a pediatrician before school entry, during a period of heightened brain plasticity when interventions are more likely to be effective. In this review, we discuss the clinical implications of the most recent advances in dyslexia research, which converge to indicate that early identification and screening are crucial to the prevention or mitigation of adverse secondary consequences of dyslexia. We further highlight evidence-based and practical strategies for the implementation of early risk identification in pediatric practice so that physicians can be empowered in their ability to treat, educate, and advocate for their patients and families with dyslexia.

Urine metals concentrations and dyslexia among children in China

BackgroundExposures to heavy metals has been linked to many developmental disorders. However, few studies have investigated the effects of exposure and co-exposure to metals on dyslexia, especially with regard to dyslexics in China. ObjectivesTo investigate the association between urine metal concentrations and dyslexia in a case-control study among children in China. MethodsA case-control study was conducted in the Tongji Reading Environment and Dyslexia (READ) research program. A total of 228 dyslexics and 228 controls were matched on gender, age (within one year), and grade. The concentrations of 21 urine metals were measured by an inductively coupled plasma-mass spectrometer (ICP-MS). Multivariable conditional logistic regression models were applied to estimate the adjusted odds ratios (ORs) of Chinese dyslexia. ResultsAfter adjusting for potential confounders, two metals (selenium and argentum) were significantly associated with dyslexia in single-metal multivariable models. Argentum was positively associated with the risk of dyslexia, while selenium was negatively associated. In the multiple-metal model, compared with extreme quartiles, the ORs (95% CIs) for selenium was 0.36 (95% CI: 0.14–0.93; Ptrend = 0.029). In the joint association analysis, children with higher levels of urine argentum and lower level of urine selenium had a significantly higher risk of dyslexia than those with low levels of argentum and selenium (OR = 5.06, 95% CI: 1.67–18.84). ConclusionsThe findings suggest that exposure to selenium and argentum may relate to dyslexia in China. Longitudinal studies are needed to further evaluate these relationships and investigate potential mechanisms.

University of Washington Reading & Dyslexia Research Program

University of Washington Reading & Dyslexia Research Program