History Of Dyslexia Research Articles

Do we really need a new definition of dyslexia? A commentary

We provide a commentary on current debates about the definition of dyslexia. We agree with others that dyslexia is best thought of as a dimensional disorder with the best established causal risk factor being a deficit in phonological processing. Dyslexia is particularly common in children from families with a history of dyslexia and in children with preschool language difficulties. We argue that definitions may differ depending upon their purpose. Traditional discrepancy definitions may be useful for research purposes, but when considering the provision of educational services discrepancy definitions are not useful since all children with reading difficulties require reading intervention regardless of their level of IQ.

Reduced audiovisual temporal sensitivity in Chinese children with dyslexia.

Temporal processing deficits regarding audiovisual cross-modal stimuli could affect children's speed and accuracy of decoding. To investigate the characteristics of audiovisual temporal sensitivity (ATS) in Chinese children, with and without developmental dyslexia and its impact on reading ability. The audiovisual simultaneity judgment and temporal order judgment tasks were performed to investigate the ATS of 106 Chinese children (53 with dyslexia) aged 8 to 12 and 37 adults without a history of dyslexia. The predictive effect of children's audiovisual time binding window on their reading ability and the effects of extra cognitive processing in the temporal order judgment task on participants' ATS were also investigated. With increasing inter-stimulus intervals, the percentage of synchronous responses in adults declined more rapidly than in children. Adults and typically developing children had significantly narrower time binding windows than children with dyslexia. The size of visual stimuli preceding auditory stimuli time binding window had a marginally significant predictive effect on children's reading fluency. Compared with the simultaneity judgment task, the extra cognitive processing of the temporal order judgment task affected children's ATS. The ATS of 8-12-year-old Chinese children is immature. Chinese children with dyslexia have lower ATS than their peers.

Do Learning Disorders Impact Clinical Measures Following Concussion?

Evaluate differences in clinical testing following concussion between adolescents with no history of learning disorder (LD) and those with a history of dyslexia and/or ADD/ADHD. Learning disorders, such as ADHD, can affect ImPACT® baseline neurocognitive testing. The effect that ADHD has on other clinical measures is less well understood. Additionally, limited data exists on the effect of dyslexia on these measures. Data were prospectively collected from participants enrolled in the North Texas Concussion Registry (ConTex). Participants ages 10-18 years old, diagnosed with a concussion sustained within 30 days of enrollment were included and assessed for self-reported history of LD type (dyslexia and/or ADD/ADHD). Clinical findings examined included symptom scores (derived from SCAT5™), ImPACT®, King-Devick (KD) test, patient health questionnaire 8(PHQ-8) scores, and generalized anxiety disorder 7(GAD-7) scores. Mann-Whitney tests were used to compare groups. In total, 1,298 participants were included: 58 with dyslexia, 158 with ADD/ADHD, 35 with both (dyslexia and ADD/ADHD), and 1,047 with no LD. There was no difference in age, sex, time since injury, or history of concussion apart from the ADD/ADHD group, which had more males (p < 0.001). The dyslexia group had slower mean KD time (p = 0.011) and increased error scores (p = 0.028). In those with ADD/ADHD, impulse control scores on ImPACT® were significantly higher (p = 0.007), but no other ImPACT® score differences reached significance. PHQ-8 and GAD-7 scores were significantly higher in those with ADD/ADHD (p < 0.001). Participants with both dyslexia and ADHD demonstrated slower KD times (p = 0.009) and had higher PHQ-8 (p < 0.001) and GAD-7 (p = 0.001) scores. Participants with dyslexia and/or ADD/ADHD had worse scores on commonly used concussion clinical measures including ImPACT® impulse control, KD testing, and depression and anxiety screenings. Understanding the differences in these groups will aid providers in their evaluation and assist in counseling families regarding the injury.

A-07 The Impact of Learning Disorders on Clinical Measures Following Concussion

Abstract Objective To examine differences in clinical measures between adolescents with dyslexia, ADD/ADHD, and those without a learning disorder (LD) following concussion. Method Data from the North Texas Concussion Registry (ConTex) were extracted. Participants ages 10–18 with a diagnosed concussion within 30 days of enrollment were included and categorized based on self-reported prior diagnosis of dyslexia, ADD/ADHD, and no history of LD. ImPACT, King-Devick (KD), SCAT-5 symptom log, Patient Health Questionnaire (PHQ-8), and Generalized Anxiety Disorder (GAD-7) scale were compared between groups using a one-way ANOVA followed by a Tukey test for multiple comparisons. Results Of 993 eligible participants, 68 had dyslexia, 141 had ADD/ADHD, and 784 had no history of LD. There were significantly more male participants in the ADD/ADHD group compared to the no LD group (64.5% vs. 50.3%, p = 0.002). No other demographic differences were noted between groups. In the dyslexia group, SCAT-5 symptom score was higher (36.22 vs. 28.27, p = 0.037) and ImPACT visual motor control was lower compared to the no LD group (28.87 vs. 32.99, p = 0.027). In the ADD/ADHD group, ImPACT symptom score was higher (30.69 vs. 20.94, p &amp;lt; 0.001) and visual motor control was lower compared to the no LD group (30.05 vs. 32.99, p = 0.009). KD time (62.1 sec), PHQ-8 (5.79), and GAD-7 (5.06) were higher in the ADD/ADHD group compared to the no LD group (56.5 sec, 4.32, 3.56; p = 0.022, p = 0.003, p = 0.002). Conclusions Differences in clinical measures were seen in participants with a history of dyslexia and ADD/ADHD that may aid providers in their evaluation following adolescent concussion.

HOW DO LEARNING DISORDERS IMPACT CLINICAL MEASURES FOLLOWING CONCUSSION?

Background:There is limited evidence examining the impact of learning disorders on testing and screening scores used in evaluation following concussion in adolescents.Purpose:To examine differences in clinical measures between adolescents with a history of dyslexia or ADD/ADHD and those without a history of learning disorder (LD) following concussion.Methods:Data were collected from participants enrolled in the North Texas Concussion Network Prospective Registry (ConTex). Participants ages 10-18 who had been diagnosed with a concussion sustained within 30 days of enrollment were included. Participants were separated into three groups based on self-reported prior diagnosis: dyslexia, ADD/ADHD, and no history of LD. Clinical measures from initial presentation were examined, including ImPACT®, King-Devick (KD), SCAT-5 symptom log, Patient Health Questionnaire (PHQ-8), and Generalized Anxiety Disorder (GAD-7) scale. Independent t-test analysis was performed to compare scores between groups.Results:A total of 993 participants were included; 68 with dyslexia, 141 with ADD/ADHD, and 784 with no history of LD. There was no difference in age, sex, time since injury, or history of concussion between the dyslexia group and no LD group. In the ADD/ADHD group, there were significantly more male participants (64.5% and 50.3% respectively, p=0.002).Participants with a history of dyslexia had a significant increase in KD time (63.7 sec vs 56.5 sec, p=0.019). Additionally, ImPACT® testing showed a decrease in visual motor speed (28.87 vs 32.99, p= 0.010). Total symptom score was higher in this group as well (36.22 vs 28.27, p=0.013).In those with a history of ADD/ADHD, multiple domains were found to be significantly different on ImPACT® testing including visual motor speed (30.05), reaction time (0.75), and cognitive efficiency (0.23) when compared to those with no LD (32.99, 0.71, and 0.27 respectively, p=0.004, 0.047, 0.027). KD time was also significantly higher in this group (62.1 sec vs 56.5 sec, p=0.008), as was the total symptom score (32.99 vs 28.27, p=0.043). PHQ-8 and GAD-7 were both significantly higher in the group with ADD/ADHD (5.79 and 5.06 respectively, p=0.001) than those with no LD (4.32 and 3.56, p=0.001).Conclusion:Differences were seen in participants with a history of dyslexia and ADD/ADHD on clinical concussion measures, including ImPACT® and KD testing, SCAT-5 symptom log, and screenings for depression and anxiety. A better understanding of the unique profiles seen in these patients will aid providers in their evaluation and assist as they counsel families regarding their child’s injury.

The role of phonology in lexical access in teenagers with a history of dyslexia.

We examined phonological recoding during silent sentence reading in teenagers with a history of dyslexia and their typically developing peers. Two experiments are reported in which participants’ eye movements were recorded as they read sentences containing correctly spelled words (e.g., church), pseudohomophones (e.g., cherch), and spelling controls (e.g., charch). In Experiment 1 we examined foveal processing of the target word/nonword stimuli, and in Experiment 2 we examined parafoveal pre-processing. There were four participant groups–older teenagers with a history of dyslexia, older typically developing teenagers who were matched for age, younger typically developing teenagers who were matched for reading level, and younger teenagers with a history of dyslexia. All four participant groups showed a pseudohomophone advantage, both from foveal processing and parafoveal pre-processing, indicating that teenagers with a history of dyslexia engage in phonological recoding for lexical identification during silent sentence reading in a comparable manner to their typically developing peers.

The Role of Memory in Dyslexia

This paper examines what the literature proffers regarding the relationship between dyslexia and memory deficiencies. Dyslexia is a well-known learning disability that has been recognized since the late 1800’s and has grown in notoriety since it was first discovered (Javier, 2015). It is especially notable due to its current prevalence among school aged children as well as adults and because of the detrimental nature that impaired literacy can have on their ability to read, write and excel academically. Discussed here are a history of dyslexia, along with a general exploration of the functions of memory and how it has to do with the processing and output of information within the mind. Two research studies are examined that help draw a direct correlation between a deficit in short-term and working memory with the phonological difficulties suffered by those who experience dyslexia. By better understanding the role of memory in dyslexia, educators may be more efficient at assisting and implementing early intervention for those children who need it.

Literacy and Phonological Skills in Oral Deaf Children and Hearing Children With a History of Dyslexia

AbstractOral deaf children and hearing children with dyslexia both experience literacy challenges, although their reasons differ. The authors explored the problems underlying poor literacy in each group and drew implications for reading interventions. Data were collected using standardized literacy and phonological measures from 69 severe‐to‐profoundly prelingually deaf children ages 10 and 11 years, all communicating with spoken language, and compared with equivalent data from 20 hearing children with a history of dyslexia matched on reading ability. Children were given a large battery of tasks assessing word and nonword reading, spelling, vocabulary, and reading‐related skills, including letter sound knowledge, phonological awareness, rapid automated naming, and verbal short‐term memory. Striking similarities were observed for word reading, nonword reading, and spelling across groups, and associations between the measures and reading‐related skills were similar. However, differences between the two groups emerged in the strength of association between literacy and vocabulary. Regression analyses confirmed vocabulary as a key predictor of literacy in the oral deaf group. These results suggest that not only children with a history of dyslexia but also oral deaf children who struggle with reading should receive specialist literacy support. Reading interventions for oral deaf children should target phonological and language skills within a fully integrated approach.

Spatiotemporal reorganization of the reading network in adult dyslexia

Developmental dyslexia is characterized by impairments in reading fluency and spelling that persist into adulthood. Here, we hypothesized that high-achieving adult dyslexics (i.e., university students with a history of dyslexia) manage to cope with these deficits by relying to a greater extent on morphological information than do non-impaired adult readers. We used magnetoencephalography (MEG) in a primed lexical decision task, in which we contrasted orthographic, morphological and semantic processing. Behavioral results confirmed that adult dyslexics did indeed rely to a greater extent on the semantic properties of morphemes than controls. In line with this, MEG results showed early morphological effects (100–200 msec) in a frontal network, which reflected the contribution of semantic processing. The same effects occurred much later in controls (∼400 msec). In contrast, controls showed early orthographic priming effects in posterior left inferior temporal gyrus (LITG) at around 130 msec, which were not seen in dyslexics. In the LITG, dyslexics showed only late activation of semantic and orthographic information. The present results suggest a spatiotemporal reorganization of the reading network, in which morphological information located in frontal regions is activated earlier in high-achieving adults dyslexics than controls.

C-45 * Do Athletes with Dyslexia Differ at Baseline and/or at Concussion Post-Injury Assessment on a Computer-Based Test Battery?

Objective: This study investigated differences in cognitive processes and symptom reporting between high school age athletes with and without a history of dyslexia. Method: A sample of 138 athletes with dyslexia (ages 14 to 18) were compared to an age and gender matched sample of 138 athletes without dyslexia. The performance of the groups was compared at baseline testing and at post-injury evaluation within one week of injury. All data was extracted from a large de-identified database of high school athletes. Data were analyzed via a repeated measures multivariate analysis of variance (MANOVA) with the presence or absence of dyslexia representing the independent variable (factor) and baseline vs. post injury evaluation representing the within subjects factor. The dependent variables consisted of the Verbal Memory, Visual Memory, Visual Motor Processing, Reaction Time, and Symptom Scale composites from the ImPACT test battery. Results: Athletes with dyslexia scored lower on all ImPACT cognitive measures (F = 12.04, p < .000001). No significant differences were found with regard to self-reported symptoms. Significant differences were found both at baseline and post injury (F = 19.60, p < .00000). Conclusion(s): Athletes with and without dyslexia differed significantly at baseline and at post-injury. This study highlights the importance of comparing the post-injury performance of dyslexic athletes to their own baseline, and the need for norms specifically on athletes with dyslexia and other learning disabilities.

The association between childhood physical abuse and dyslexia: findings from a population-based study.

The objective of this study was to determine the relationship between a history of dyslexia and childhood physical abuse in a large population-based epidemiological sample. It was hypothesized that the prevalence of dyslexia would be significantly higher in individuals who reported a childhood history of physical abuse in comparison to those who did not report such a history. A secondary analysis examined data from respondents 18 years and older from the Saskatchewan and Manitoba sample of the 2005 Canadian Community Health Survey (CCHS). There were 13,640 respondents ages 18 and older. Due to missing data, the final sample size was 13,054 respondents. One third (34.8%) of respondents who reported they had been physically abused during their childhood or adolescence also reported being diagnosed with dyslexia in comparison with 7.2% of those who did not report being physically abused (p < .001). Initial adjustments for sociodemographic variables produced an odds ratio (OR) for dyslexia that was more than 7 times higher (OR = 7.09; 95% confidence interval [CI] = [4.42, 11.35]) for those who had reported being physically abused in comparison with their peers who did not report such a history; with additional adjustments for other adverse childhood experiences, these odds decreased only slightly to 6.09 times higher (95% CI = [3.58, 10.35]). Further research is needed to understand the mechanism linking physical abuse and dyslexia.

CNVs conferring risk of autism or schizophrenia affect cognition in controls

In a small fraction of patients with schizophrenia or autism, alleles of copy-number variants (CNVs) in their genomes are probably the strongest factors contributing to the pathogenesis of the disease. These CNVs may provide an entry point for investigations into the mechanisms of brain function and dysfunction alike. They are not fully penetrant and offer an opportunity to study their effects separate from that of manifest disease. Here we show in an Icelandic sample that a few of the CNVs clearly alter fecundity (measured as the number of children by age 45). Furthermore, we use various tests of cognitive function to demonstrate that control subjects carrying the CNVs perform at a level that is between that of schizophrenia patients and population controls. The CNVs do not all affect the same cognitive domains, hence the cognitive deficits that drive or accompany the pathogenesis vary from one CNV to another. Controls carrying the chromosome 15q11.2 deletion between breakpoints 1 and 2 (15q11.2(BP1-BP2) deletion) have a history of dyslexia and dyscalculia, even after adjusting for IQ in the analysis, and the CNV only confers modest effects on other cognitive traits. The 15q11.2(BP1-BP2) deletion affects brain structure in a pattern consistent with both that observed during first-episode psychosis in schizophrenia and that of structural correlates in dyslexia.

Cognitive Endophenotypes of Dyslexia

The study investigated cognitive deficits associated with dyslexia and familial risk of dyslexia (endophenotypes) by comparing children from families with and without a history of dyslexia. Eighty-eight school-aged children were assessed on measures of phonology, language and rapid automatized naming. A series of regression analyses with family risk and dyslexia status as predictors indicated that word recall, morphology, and rapid automatized naming were associated with the deficit, whereas the two phonological measures (phoneme awareness and nonword repetition) were associated with both literacy deficits and family risk, suggesting that the phonological deficit is an endophenotype of dyslexia. Whereas the association with familial risk was similar for the two phonological measures, they differed in their relation to dyslexia status: Phoneme awareness showed a stronger association with dyslexia than risk status, whereas nonword repetition was more strongly related to the risk. The data are interpreted within the framework of multiple deficit models of dyslexia.

The Reading Brain

Neuroscience Developmental dyslexia, which manifests as difficulty with reading, can have long-lasting and detrimental effects on a child's experience with education, with echoes that persist long into adulthood. Raschle et al. have leveraged the indications of familial risk for dyslexia to distinguish differences in brain structure present before reading from those that arise after the battle with reading difficulties is well engaged. The authors studied a total of 36 5-year-old children, all pre-literate, characterized by whether or not their family had a history of dyslexia. Even at these pre-reading ages, functional brain imaging revealed an aberrant signal similar to that found in older children with a confirmed diagnosis of dyslexia. Development of the brain network supporting phonological processing appeared to be delayed. On the other hand, the two groups of children showed no difference in other networks that are hyperactivated when persons with dyslexia are reading. Those networks may instead represent compensation brought into play in the struggle to defeat reading difficulties. Proc. Natl. Acad. Sci. U.S.A. 109 , 2156 (2012).

Child and parental literacy levels within families with a history of dyslexia

The present study concerns literacy and its underlying cognitive skills in Dutch children who differ in familial risk (FR) for dyslexia. Previous studies with FR-children were inconclusive regarding the performance of FR-children without dyslexia as compared to the controls. Moreover, van Bergen et al. (2011) recently showed that FR-children with and without dyslexia differed in parental reading skills, suggesting that those who go on to develop dyslexia have a higher liability. The current study concerned 1) the comparison of three groups of children at the end of second grade and 2) the intergenerational transfer of reading and its underlying cognitive skills from parent to child. Three groups of children were studied at the end of second grade: FR-dyslexia (n = 42), FR-no-dyslexia (n = 99), and control children (n = 66). Parents and children were measured on naming, phonology, spelling, and word and pseudoword reading. The FR-dyslexia children were severely impaired across all tasks. The FR-no-dyslexia children performed better than the FR-dyslexia children, but still below the level of the controls on all tasks; the only exception was rapid naming (RAN), on which they were as fast as the controls. Focusing on the FR subsample, parental reading and RAN were related to their offspring's reading status. We replicated and extended van Bergen et al.'s study in showing that the FR-children who develop dyslexia are likely to have a higher liability. Both the group comparisons and the parent-child relations highlight the importance of good RAN skills for reading acquisition.

Increased left prefrontal activation during an auditory language task in adolescents born preterm at high risk

Although individuals born preterm are at risk for cognitive dysfunction, few studies have examined functional brain reorganization in these individuals. We used magnetoencephalography (MEG) to examine cortical reorganization related to preterm birth. Thirty-one adolescents systemically selected from a longitudinal study on child development based on gestational age, birth weight and medical complications (full term, low risk preterm, high-risk preterm) performed real-word and non-word auditory rhyme tasks during MEG recording. Equivalent current dipoles were localized every 4 ms during the 50- to 250-ms period following the onset of the auditory stimulus. The association between the number of dipoles (NODs) and birth group, language task, latency and phonological skills was examined. Adolescents born preterm at high risk demonstrated a greater NODs in the left Broca's and prefrontal areas combined, left cingulate gyrus and left superior temporal gyrus and a fewer NODs in the right superior temporal gyrus as compared to those born preterm at low risk and term. A greater NODs in the left Broca's and prefrontal areas combined and fewer NODs in the left cingulate gyrus was associated with better phonological skills only in adolescents born preterm at high risk. These results suggest that the language networks are reorganized in adolescents born preterm at high risk. Increased prefrontal activity has also been seen in adolescents born preterm during a reading task and in young adults with a history of dyslexia who are well compensated for their disorder. We suggest that this increased prefrontal activation may represent increased top–down control of weak posterior language networks.

Surface Area Accounts for the Relation of Gray Matter Volume to Reading-Related Skills and History of Dyslexia

It is unknown whether the abnormalities in brain structure and function observed in dyslexic readers are congenital or arise later in development. Analyzing the 2 components of gray matter volume separately may help in differentiating these possibilities. Gray matter volume is the product of cortical surface area, determined during prenatal brain development, and cortical thickness, determined during postnatal development. For this study, 16 adults with a history of phonological dyslexia and 16 age- and gender-matched controls underwent magnetic resonance imaging and an extensive battery of tests of reading-related skills. Cortical surface area and gray matter volume measures of the whole brain, the inferior frontal gyrus, and the fusiform gyrus were similarly related to phonological skills and a history of dyslexia. There was no relationship between cortical thickness and phonological skills or history of dyslexia. Because cortical surface area reflects cortical folding patterns determined prenatally, this suggests that brain differences in dyslexia are rooted in early cortical development and are not due to compensatory changes that occur during postnatal development and would be expected to influence cortical thickness. This study demonstrates the importance of examining the separate components of gray matter volume when studying developmental abnormalities.

Art students who cannot draw: Exploring the relations between drawing ability, visual memory, accuracy of copying, and dyslexia.

Some art students, despite being at art school, cannot draw very well, and would like to be able to draw well. It has been suggested that poor drawing may be a particular problem for students with dyslexia (and a high proportion of art school students is dyslexic). In Study 1 we studied 277 art students, using a questionnaire to assess self-perceived drawing ability and a range of background measures, including demography, education, a history of dyslexia, a self-administered spelling test, and personality and educational variables. In Study 2 we gave detailed drawing tests to a sample of 38 of the art students, stratified by self-rated drawing ability and spelling ability, and to 30 control participants. Students perceiving themselves as good at drawing did indeed draw better than self-perceived poor drawers, although the latter were still better than non-art student controls. In neither Study 1 nor Study 2 did skill at drawing relate to dyslexia or spelling ability, and neither did drawing ability relate to any of our wide range of background measures. However Study 2 did show that drawing ability was related both to ability at copying simple angles and proportions (using the “house” task of Cain, 1943), and also to visual memory (as suggested by Jones, 1922), poor drawers being less good at both immediate and delayed recall of the Rey-Osterrieth complex figure.

Dyslexic entrepreneurs: the incidence; their coping strategies and their business skills

This comparative study explores the incidence of dyslexia in entrepreneurs, corporate managers and the general population. It examines the suggestion that dyslexic entrepreneurs develop coping strategies to manage their weaknesses, which are subsequently of benefit in the new venture creation process. Results of this study suggest that there is a significantly higher incidence of dyslexia in entrepreneurs than in the corporate management and general US and UK populations and some of the strategies they adopt to overcome dyslexia (such as delegation of tasks) may be useful in business. The study was undertaken in two parts. First, entrepreneurs and corporate managers completed an online questionnaire, which combined questions about their company, their management or leadership role and their business skills together with questions that were designed to explore the likely incidence of dyslexia. A follow-up study that made use of a semi-structured questionnaire explored business issues and educational experience in more depth with those who had been diagnosed as dyslexic and those who did not have any history of dyslexia or any other learning difficulty.

Asymmetry of voice onset time-processing in adult developmental dyslexics

Objective The human auditory cortex codes speech temporally according to sequential acoustico-phonetic cues like the voice onset time (VOT). This coding is predominantly left-lateralized in normal readers. We examined VOT-processing asymmetries in adults with a history of developmental dyslexia (DD-history+). Methods Auditory-evoked potentials (AEPs) to voiced (/ba/) and voiceless (/pa/) speech stimuli were recorded from 10 DD-history+ adults and 8 controls. Source modelling of the “release component” (RC: ∼240 ms; time-locked to voiced consonantal release and considered reflective of VOT-processing) was conducted to explore VOT asymmetries. Results Controls demonstrated L > R RC source probe amplitude asymmetry in the auditory cortex. DD-history+ subjects with little persistent reading deficit ( n = 5) demonstrated normal temporal coding but rightward asymmetry. DD-history+ subjects with severe persistent deficits ( n = 5) exhibited numerous supplemental AEP components (notably left hemispheric) and inconsistent asymmetry (leftward or alternating). Conclusions These preliminary findings suggest that DD-history+ adults process auditory speech cues differently than adults without previous DD. The nature of this processing may relate to the severity of persistent reading deficits. Significance Previous dyslexics with little persistent deficit can exhibit atypical functional asymmetry with normal auditory temporal coding. Source modelling represents an effective, non-invasive means of exploring processing asymmetries in clinical populations.