Parental education moderates genetic influences on reading disability

Interaction between Risk Single-Nucleotide Polymorphisms of Developmental Dyslexia and Parental Education on Reading Ability: Evidence for Differential Susceptibility Theory

While genetic and environmental factors have been shown as predictors of children's reading ability, the interaction effects of identified genetic risk susceptibility and the specified environment for reading ability have rarely been investigated. The current study assessed potential gene-environment (G×E) interactions on reading ability in 1477 school-aged children. The gene-environment interactions on character recognition were investigated by an exploratory analysis between the risk single-nucleotide polymorphisms (SNPs), which were discovered by previous genome-wide association studies of developmental dyslexia (DD), and parental education (PE). The re-parameterized regression analysis suggested that this G×E interaction conformed to the strong differential susceptibility model. The results showed that rs281238 exhibits a significant interaction with PE on character recognition. Children with the "T" genotype profited from high PE, whereas they performed worse in low PE environments, but "CC" genotype children were not malleable in different PE environments. This study provided initial evidence for how the significant SNPs in developmental dyslexia GWA studies affect children's reading performance by interacting with the environmental factor of parental education.

Longitudinal associations between language network characteristics in the infant brain and school-age reading abilities are mediated by early-developing phonological skills

Reading acquisition is a prolonged learning process relying on language development starting in utero. Behavioral longitudinal studies reveal prospective associations between infant language abilities and preschool/kindergarten phonological development that relates to subsequent reading performance. While recent pediatric neuroimaging work has begun to characterize the neural network underlying language development in infants, how this neural network scaffolds long-term language and reading acquisition remains unknown. We addressed this question in a 7-year longitudinal study from infancy to school-age. Seventy-six infants completed resting-state fMRI scanning, and underwent standardized language assessments in kindergarten. Of this larger cohort, forty-one were further assessed on their emergent word reading abilities after receiving formal reading instructions. Hierarchical clustering analyses identified a modular infant language network in which functional connectivity (FC) of the inferior frontal module prospectively correlated with kindergarten-age phonological skills and emergent word reading abilities. These correlations were obtained when controlling for infant age at scan, nonverbal IQ and parental education. Furthermore, kindergarten-age phonological skills mediated the relationship between infant FC and school-age reading abilities, implying a critical mid-way milestone for long-term reading development from infancy. Overall, our findings illuminate the neurobiological mechanisms by which infant language capacities could scaffold long-term reading acquisition.

Longitudinal associations between language network characteristics in the infant brain and school-age reading abilities are mediated by early-developing phonological skills

Reading acquisition is a prolonged learning process relying on language development starting in utero. Behavioral longitudinal studies reveal prospective associations between infant language abilities and preschool/kindergarten phonological development that relates to subsequent reading performance. While recent pediatric neuroimaging work has begun to characterize the neural network underlying language development in infants, how this neural network scaffolds long-term language and reading acquisition remains unknown. We addressed this question in a 7-year longitudinal study from infancy to school-age. Seventy-six infants completed resting-state fMRI scanning, and underwent standardized language assessments in kindergarten. Of this larger cohort, forty-one were further assessed on their emergent word reading abilities after receiving formal reading instructions. Hierarchical clustering analyses identified a modular infant language network in which functional connectivity (FC) of the inferior frontal module prospectively correlated with kindergarten-age phonological skills and emergent word reading abilities. These correlations were obtained when controlling for infant age at scan, nonverbal IQ and parental education. Furthermore, kindergarten-age phonological skills mediated the relationship between infant FC and school-age reading abilities, implying a critical mid-way milestone for long-term reading development from infancy. Overall, our findings illuminate the neurobiological mechanisms by which infant language capacities could scaffold long-term reading acquisition.

Caregiver Self-Efficacy in Relation to Caregivers' History of Language and Reading Difficulties and Children's Shared Reading Experiences

PURPOSE

Emerging literature suggests caregiver self-efficacy is an important factor related to caregivers' shared reading practices with their children. Reduced shared reading has been documented among families of caregiver(s) with language-based learning disabilities (LBLD). Yet, it remains unclear whether caregivers' history of language and reading difficulties is associated with caregiver self-efficacy. The purpose of this study was to examine whether self-efficacy in language- and reading-related caregiver activities related to caregiver history of language and reading difficulties and shared reading practices.

METHOD

One hundred seventy-six caregivers of children aged 18-60 months completed a custom self-efficacy in language- and reading-related caregiver activities questionnaire, as well as demographic, history of language and reading difficulties (used both as a continuous measure and to dichotomize caregivers with and without LBLD history), and shared reading measures in a one-time survey.

RESULTS

Caregivers with a history of LBLD reported an overall lower self-efficacy and a reduced amount of time reading with their children per week than caregivers without LBLD history. Examining caregiver history of language and reading difficulties continuously across the whole group, self-efficacy mediated the relationship between caregiver difficulties and shared reading practices, even when caregiver education was incorporated as an additional mediator in models.

CONCLUSIONS

Findings indicate that self-efficacy and caregiver education mediate the relationship between caregiver history of language and reading difficulties and shared reading practices. Consideration of self-efficacy by clinicians and educators is warranted when promoting shared reading practices to caregivers of young children. There is a need for future research to examine relationships between self-efficacy and shared reading among caregivers with LBLD of culturally and linguistically diverse backgrounds.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.25901590.

Phonological awareness mediates the relationship between DCDC2 and reading performance with home environment

Proficient reading requires critical phonological processing skill that interacts with both genetic and environmental factors. However, the precise nature of the relationships between phonological processing and genetic and environmental factors are poorly understood. We analyzed data from the Genes, Reading and Dyslexia (GRaD) Study on 1419 children ages 8-15 years from African-American and Hispanic-American family backgrounds living in North America. The analyses showed that phonological awareness mediated the relationship between DCDC2-READ1 and reading outcomes when parental education and socioeconomic status was low. The association between READ1 and reading performance is complex, whereby mediation by phonological awareness was significantly moderated by both parental education and socioeconomic status. These results show the importance of home environment and phonological skills when determining associations between READ1 and reading outcomes. This will be an important consideration in the development of genetic screening for risk of reading disability.

From classroom to life: Gender differences in the persistent effect of learning disabilities on adult depressive symptoms

Despite the well-established link between adolescent learning disabilities (LD) and mental health, little is known about its long-term consequences. This study examines the relationship between adolescent LD and adult depressive symptoms, with a focus on gender differences and underlying mechanisms. Using a sibling sample from the National Longitudinal Study of Adolescent to Adult Health (N = 3,414), this study estimated sibling fixed effects models to account for unobserved family-level characteristics such as genes and early childhood family and social context. Sobel mediation analyses were conducted to examine social-psychological mechanisms, including the student-teacher relationship, the student-student relationship, and a sense of school belonging. LD in adolescence was positively associated with depressive symptoms in adulthood (b = 0.823, p < 0.05). This association remained robust when controlling for unobserved family-level confounders as well as educational attainment in adulthood. Gender-stratified models showed that only the association for women is statistically significant (b = 1.935, p < 0.05), and its magnitude is nearly three times that of the association for men. Sobel mediation tests indicate that a decline in a sense of school belonging mediates approximately 17% of the association between adolescent LD and adult depressive symptoms. This study's findings suggest that LD in adolescence is associated with an increase in depressive symptoms in adulthood, particularly in women, and a low sense of school belonging may be a potential mediator. Implementing interventions to improve the school integration of girls with LD could be an effective means of improving their long-term mental health.

A Longitudinal Analysis of Gene x Environment Interaction on Verbal Intelligence Across Adolescence and Early Adulthood

The Scarr-Rowe hypothesis proposes that the heritability of intelligence is higher in more advantaged socioeconomic contexts. An early demonstration of this hypothesis was Rowe and colleagues (Rowe et al., Child Dev 70:1151-1162, 1999), where an interaction between the heritability of verbal intelligence and parental education was identified in adolescent siblings in Wave I of the National Longitudinal Study of Adolescent to Adult Health. The present study repeated their original analysis at Wave I using contemporary methods, replicated the finding during young adulthood at Wave III, and analyzed the interaction longitudinally utilizing multiple measurements. We examined parental education, family income, and peer academic environment as potential moderators. Results indicated increased heritability and decreased shared environmental variance of verbal intelligence at higher levels of parental education and peer academic environment in adolescence. Moreover, moderation by peer academic environment persisted into adulthood with its effect partially attributable to novel gene-environment interactions that arose in the process of cognitive development.

Spelling Proficiency of Children with a Resolved Phonological Speech Sound Disorder Treated with an Integrated Approach-A Long-Term Follow-Up Randomized Controlled Trial

Phonological developmental speech sound disorders (pDSSD) in childhood are often associated with later difficulties in literacy acquisition. The present study is a follow-up of the randomized controlled trial (RCT) on the effectiveness of PhonoSens, a treatment for pDSSD that focuses on improving auditory self-monitoring skills and categorial perception of phoneme contrasts, which could have a positive impact on later spelling development. Our study examines the spelling abilities of 26 German-speaking children (15 girls, 11 boys; mean age 10.1 years, range 9.3-11.2 years) 3-6 years after their successful completion of the PhonoSens treatment. Spelling assessment revealed that only 3 out of 26 participants developed a spelling disorder. In the overall population of fourth-graders, one in five children showed a spelling deficit; in another study of elementary school children, with resolved pDSSD, 18 of 32 children had a spelling deficit. Thus, the applied pDSSD treatment method appears to be associated with positive spelling development. Multiple regression analysis revealed that among the potentially predictive factors for German-speaking children with resolved pDSSD to develop later spelling difficulties, parental educational level and family risk for developmental language disorder (DLD) had an impact on children's spelling abilities; gender and the child's phonological memory had not.

Phonological Awareness Mediates the Relationship between DCDC2 and Reading Performance with the Influence of Home Environment

Proficient reading requires critical phonological processing skill that interact with both genetic and environmental factors. However, the precise nature of the relationships between phonological processing and genetic and environmental factors are poorly understood. We analyzed data from the Genes, Reading and Dyslexia (GRaD) Study on 1,419 children ages 8 to 14 years from African-American and Hispanic-American family backgrounds living in North America. The analyses showed that phonological awareness mediated the relationship between DCDC2-READ1 and reading outcomes when parental education and socioeconomic status was low. The association between READ1 and reading performance is complex, whereby mediation by phonological awareness was significantly moderated by both parental education and socioeconomic status. These results show the importance of home environment and phonological skills when determining associations between READ1 and reading outcomes. This will be an important consideration in the development of genetic screening for risk of reading disability.

Bioenvironmental Predictors of Childhood Reading and Speech Difficulties

PURPOSE

Reading and speech difficulties are common in childhood, yet it is not fully understood how much of their etiology is shared. This partly derives from methodological issues related to overlooking the potential co-occurrence between the two sets of difficulties. This study investigated the effects of five bioenvironmental predictors in a sample assessed for such co-occurrence.

METHOD

A combination of exploratory and confirmatory analyses was performed on longitudinal data from the National Child Development Study. Exploratory latent class analysis was performed on children's reading, speech, and language outcomes at ages 7 and 11 years. Membership in the obtained classes was modeled using a regression with sex and four early-life predictors: gestation period, socioeconomic status, maternal education, and the home reading environment.

RESULTS

The model yielded four latent classes that broadly reflected (1) average reading and speech, (2) excellent reading, (3) reading difficulties, and (4) speech difficulties. Early-life factors significantly predicted class membership. Male sex and preterm birth emerged as risk factors for both reading and speech difficulties. Protective effects against reading difficulties were identified for maternal education, and lower (but not higher) levels of socioeconomic status and the home reading environment.

CONCLUSIONS

Co-occurrence of reading and speech difficulties in the sample was low, and differential patterns of effect of the social environment were supported. Reading outcomes were under stronger malleable influence than speech outcomes.

The nature-nurture of academic achievement at the intersection between gender, family background, and school context

We investigate the role of gender, family SES, school SES, and their intersection in educational achievement using a twin design. Drawing on theories of gene-environment interaction, we test whether high-SES environments compensate genetic risks or enhance genetic potential, and its dependency on gender. Using data on 37,000 Danish twin and sibling pairs from population-wide administrative registers, we report three main findings. First, for family SES, but not for school SES, we find that genetic influences play a slightly smaller role in high-SES environments. Second, this relationship is moderated by child gender: in high-SES families, the genetic influence is considerably lower for boys than for girls. Third, the moderating effect of family SES for boys is almost entirely driven by children attending low-SES schools. Our findings thus point to significant heterogeneity in gene-environment interactions, highlighting the importance of considering the multiplicity of social contexts.

The multiple-level framework of developmental dyslexia: the long trace from a neurodevelopmental deficit to an impaired cultural technique

Developmental dyslexia is a neurodevelopmental disorder characterized by an unexpected impairment in literacy acquisition leading to specific poor academic achievement and possible secondary symptoms. The multi-level framework of developmental dyslexia considers five levels of a causal pathway on which a given genotype is expressed and hierarchically transmitted from one level to the next under the increasing influence of individual learning-relevant traits and environmental factors moderated by cultural conditions. These levels are the neurobiological, the information processing and the skill level (prerequisites and acquisition of literacy skills), the academic achievement level and the level of secondary effects. Various risk factors are present at each level within the assumed causal pathway and can increase the likelihood of exhibiting developmental dyslexia. Transition from one level to the next is neither unidirectional nor inevitable. This fact has direct implications for prevention and intervention which can mitigate transitions from one level to the next. In this paper, various evidence-based theories and findings regarding deficits at different levels are placed in the proposed framework. In addition, the moderating effect of cultural impact at and between information processing and skill levels are further elaborated based on a review of findings regarding influences of different writing systems and orthographies. These differences impose culture-specific demands for literacy-specific cognitive procedures, influencing both literacy acquisition and the manifestation of developmental dyslexia.

Socioeconomic dissociations in the neural and cognitive bases of reading disorders

Childhood socioeconomic status (SES) strongly predicts disparities in reading development, yet it is unknown whether early environments also moderate the cognitive and neurobiological bases of reading disorders (RD) such as dyslexia, the most prevalent learning disability. SES-diverse 6-9-year-old children (n = 155, half with RD) completed behavioral and functional magnetic resonance imaging (fMRI) tasks engaging phonological and orthographic processing, which revealed corresponding double-dissociations in neurocognitive deficits. At the higher end of the SES spectrum, RD was most strongly explained by differences in phonological skill and corresponding activation in left inferior frontal and temporoparietal regions during phonological processing-widely considered the "core deficit" of RD. However, at the lower end of the SES spectrum, RD was most strongly explained by differences in rapid naming skills and corresponding activation in left temporoparietal and fusiform regions during orthographic processing. Findings indicate that children's early environments systematically moderate the neurocognitive systems underlying RD, which has implications for assessment and treatment approaches to reduce SES disparities in RD outcomes. Further, results suggest that reliance on high-SES convenience samples may mask critical heterogeneity in the foundations of both typical and disordered reading development.

Home language and literacy environment and its relationship to socioeconomic status and white matter structure in infancy

The home language and literacy environment (HLLE) in infancy has been associated with subsequent pre-literacy skill development and HLLE at preschool-age has been shown to correlate with white matter organization in tracts that subserve pre-reading and reading skills. Furthermore, childhood socioeconomic status (SES) has been linked with both HLLE and white matter organization. It is important to understand whether the relationships between environmental factors such as HLLE and SES and white matter organization can be detected as early as infancy, as this period is characterized by rapid brain development that may make white matter pathways particularly susceptible to these early experiences. Here, we hypothesized that HLLE (1) relates to white matter organization in pre-reading and reading-related tracts in infants, and (2) mediates a link between SES and white matter organization. To test these hypotheses, infants (mean age: 8.6 ± 2.3 months, N = 38) underwent diffusion-weighted imaging MRI during natural sleep. Image processing was performed with an infant-specific pipeline and fractional anisotropy (FA) was estimated from the arcuate fasciculus (AF) and superior longitudinal fasciculus (SLF) bilaterally using the baby automated fiber quantification method. HLLE was measured with the Reading subscale of the StimQ (StimQ-Reading) and SES was measured with years of maternal education. Self-reported maternal reading ability was also quantified and applied to our statistical models as a proxy for confounding genetic effects. StimQ-Reading positively correlated with FA in left AF and to maternal education, but did not mediate the relationship between them. Taken together, these findings underscore the importance of considering HLLE from the start of life and may inform novel prevention and intervention strategies to support developing infants during a period of heightened brain plasticity.

Orthographic Depth May Influence the Degree of Severity of Maze Learning Performance in Children at Risk for Reading Disorder

Reading disability (RD), which affects between 5 and 17% of the population worldwide, is the most prevalent form of learning disability, and is associated with underactivation of a universal reading network in children. However, recent research suggests there are differences in learning rates on cognitive predictors of reading performance, as well as differences in activation patterns within the reading neural network, based on orthographic depth (i.e., transparent/shallow vs. deep/opaque orthographies) in children with RD. Recently, we showed that native English-speaking children with RD exhibit impaired performance on a maze learning task that taps into the same neural networks that are activated during reading. In addition, we demonstrated that genetic risk for RD strengthens the relationship between reading impairment and maze learning performance. However, it is unclear whether the results from these studies can be broadly applied to children from other language orthographies. In this study, we examined whether low reading skill was associated with poor maze learning performance in native English-speaking and native German-speaking children, and the influence of genetic risk for RD on cognition and behavior. In addition, we investigated the link between genetic risk and performance on this task in an orthographically diverse sample of children attending an English-speaking international school in Germany. The results from our data suggest that children with low reading skill, or with a genetic risk for reading impairment, exhibit impaired performance on the maze learning task, regardless of orthographic depth. However, these data also suggest that orthographic depth influences the degree of impairment on this task. The maze learning task requires the involvement of various cognitive processes and neural networks that underlie reading, but is not influenced by potential differences in reading experience due to lack of text or oral reporting. As a fully automated tool, it does not require specialized training to administer, and current results suggest it may be a practicable screening tool for early identification of reading impairment across orthographies.

Gene-Environment Interactions in Attention-Deficit/Hyperactivity Disorder Symptom Dimensions: The Role of Unhealthy Food Habits

Background: Dietary habits were investigated as environmental risk factors for Attention-Deficit/Hyperactivity Disorder (ADHD). However, no previous studies explored the effects of dietary factors on modifying the role of genetic factors on ADHD. Methods: Based on a Swedish population-based twin study with 1518 twin pairs aged 20-47 years, we tested whether the importance of genetic and environmental effects on ADHD varied as a function of dietary habits. Self-reported dietary habits and ADHD symptoms were collected. Twin methods were used to test the degree to which high-sugar and unhealthy food intake moderated the genetic and environmental influences on ADHD symptoms. Results: In middle-aged adults, genetic influences on inattention symptoms were statistically significantly higher among individuals with higher levels of high-sugar (45%, 95%CI: 25-54%) and unhealthy food intake (51%, 95%CI: 31-60%), compared with those with lower levels of consumption of high-sugar (36%, 95%CI: 25-47%) and unhealthy foods (30%, 95%CI: 20-41%). Similar patterns were also found for the associations between hyperactivity/impulsivity and high-sugar/unhealthy food intake, even though the moderation effects were not statistically significant. Conclusion The present study suggests that genetic factors play a more prominent role in individual differences of ADHD symptoms in the presence of the high consumption of sugar and unhealthy foods. Future longitudinal studies with multiple assessments of ADHD and dietary habits are needed to replicate our findings.

How Learning to Read Changes the Listening Brain

Reading acquisition reorganizes existing brain networks for speech and visual processing to form novel audio-visual language representations. This requires substantial cortical plasticity that is reflected in changes in brain activation and functional as well as structural connectivity between brain areas. The extent to which a child's brain can accommodate these changes may underlie the high variability in reading outcome in both typical and dyslexic readers. In this review, we focus on reading-induced functional changes of the dorsal speech network in particular and discuss how its reciprocal interactions with the ventral reading network contributes to reading outcome. We discuss how the dynamic and intertwined development of both reading networks may be best captured by approaching reading from a skill learning perspective, using audio-visual learning paradigms and longitudinal designs to follow neuro-behavioral changes while children's reading skills unfold.

Second Graders' Grapho-Motor Skill Learning and Verbal Learning: The Effects of Socio-Educational Factors

Introduction: Children from low socioeconomic status (SES) families, and in particular, those with a lower level of maternal education, show lower fine-motor skills and lower vocabulary scores than their SES peers whose mothers have a higher level of education. Furthermore, low SES children frequently have difficulties in reading and spelling. These difficulties are attributed to deficits in the acquisition of skills through practice, such as those required for developing visual-motor routines, alongside deficits in the intentional acquisition of knowledge, such as those required in verbal learning. The aim of the current study was to test the effect of two background factors: low maternal education (ME) and risk of reading and spelling difficulties on practice-dependent learning of a motor task and intentional learning of a verbal task in second graders from low SES families. Methods: In 2016/17, 134 low-SES second graders with higher and lower ME (95 typical learners and 39 with reading and spelling difficulties) were assessed with (a) the Invented Letter Task (ILT; a grapho-motor skill learning task) across five time-points (initial- and end-training Day 1; initial- and end-training Day 2; and 2-weeks post-training), as well as an ILT transfer task; and (b) The Rey Auditory Verbal Learning Test (RAVLT; an intentional word-learning task in which a word list is read to children for five learning trials and is recalled 20 min later). Findings: Lower ME was associated with surplus segments in the performance of the motor task and its transfer to a novel condition as well as with lower recall on the verbal task, but not with the learning of both the motor and the verbal task. Having reading and spelling difficulties affected motor-task accuracy and also the way children learned the task, as evidenced by surplus segments at the beginning of Day 2, which were reduced with further practice. Conclusion: Low ME affected overall performance level. Reading and spelling difficulties resulted in atypical learning of the motor task. Future research on practice-dependent learning in the context of children coming from low SES families should focus on subgroups within this heterogeneous population.

Animal models of developmental dyslexia: Where we are and what we are missing

Developmental dyslexia (DD) is a complex neurodevelopmental disorder and the most common learning disability among both school-aged children and across languages. Recently, sensory and cognitive mechanisms have been reported to be potential endophenotypes (EPs) for DD, and nine DD-candidate genes have been identified. Animal models have been used to investigate the etiopathological pathways that underlie the development of complex traits, as they enable the effects of genetic and/or environmental manipulations to be evaluated. Animal research designs have also been linked to cutting-edge clinical research questions by capitalizing on the use of EPs. For the present scoping review, we reviewed previous studies of murine models investigating the effects of DD-candidate genes. Moreover, we highlighted the use of animal models as an innovative way to unravel new insights behind the pathophysiology of reading (dis)ability and to assess cutting-edge preclinical models.

Dyslexia knowledge, perceived preparedness, and professional development needs of in-service educators

The purpose of this study was to investigate New Jersey educators' dyslexia knowledge and misconceptions, professional development perceptions and needs, and perceived preparedness regarding teaching students with dyslexia. A second purpose was to investigate what factors predicted New Jersey educators' knowledge about dyslexia. A total of 705 in-service educators completed a survey about their dyslexia knowledge, perceived preparedness, and professional development perceptions. Participants had accurate overall knowledge about dyslexia, but some prevailing misconceptions were still present. The greatest predictor of dyslexia knowledge was years of experience in working with students with dyslexia. Reading specialists, educators with greater perceived preparedness and those educators who had training in multi-sensory approaches to instruction had significantly more dyslexia knowledge than other educators. Approximately half of the participants felt prepared to teach students with dyslexia and that working with students with dyslexia prepared them the most. Participants perceived that multi-sensory approaches were the most effective professional development and their undergraduate education was the least effective. Most participants were in support of further professional development on the topic of dyslexia. Implications for in-service educators' professional development and future research directions are discussed.

Current Research Informing the Conceptualization, Identification, and Treatment of Dyslexia Across Orthographies: An Introduction to the Special Series

This introduction to the special series summarizes evidence for the genetic and brain bases for dyslexia and cognitive-behavioral indicators (including ones that can be measured even before the onset of reading instruction) that attest to meaningful differences between children with dyslexia and their non-dyslexic peers. Authors review controversies that have surrounded approaches to dyslexia identification and treatment during the last few decades. Finally, they introduce the findings of the articles in the special series and discuss potential implications for dyslexia identification and treatment.

Differential Patterns of Growth in Reading and Math Skills during Elementary School

This study investigated developmental trajectories of reading and math using latent-growth-curve analyses across multiple academic skills, measures, and multiple time periods within a single sample. Reading-related growth was marked by significant individual differences during the early elementary-school period and non-significant individual differences during the late elementary-school period. For math-related skills, non-significant individual differences were present for early math growth and significant individual differences were present in late elementary-school. No clear pattern of cumulative, compensatory, or stable development emerged for either reading-related or math skills. These differing growth patterns highlight developmental complexities and suggest domain-specific differences in achievement growth that are potentially associated with contextual factors.

Priorities in the Interdisciplinary Approach of Specific Learning Disorders (SLD) in Children with Type I Diabetes Mellitus (T1DM). From Theory to Practice

BACKGROUND

A considerable endeavor had taken place in order to understand the associated challenges for children and adolescents with Specific Learning Disorder (SLD) and Type 1 Diabetes Mellitus (T1DM) but also in order to describe the necessary skills and approaches that the care givers have to develop to assist both children and parents. (1) Aim: The aim of this review is twofold. Firstly, to highlight the T1DM's potential impact on psychological well-being, on cognitive functioning and on school performance in children and adolescents who confront SLD. Secondly, to discuss the necessity of a multidiscipline approach of poor school performance in students with SLD and T1DM, presenting the serious contribution of care providers: (a) parents/carers in the family setting, (b) teachers and psychologists in the school setting and (c) health specialists (pediatricians, nutricians, nurses, child psychiatrists and psychologists) in the medical setting. (2) Methods: In this narrative literature review of 12 selected articles, each one studies a special aspect of approach, during the diagnosis and the treatment of individuals with T1DM and SLD. The review concerns the arising problems and difficulties in the adherence to diagnosis, the management of insulin, the mental and physical wellbeing, the school performance, the cognitive functioning and learning difficulties of patients. We tried to synthesize an interdisciplinary approach that involves collaboration between family, school and medical frame; facilitating children's and adolescents' difficulties management, as well as parent and teacher involvement during the intervention implementation. (3) Results: The main issues of concern were examined through the available literature, as different factors had to be re-examined in the previous studies, regarding the potential impact of T1DM in cognitive and psychological functioning, as well as the effects of the intervention/approach/treatment of children and adolescents with SLD and T1DM. (4) Conclusions: Although T1DM diagnosis and demanding treatment are a heavy burden for children and their families, T1DM may or may not be associated with a variety of academic and psychological outcomes. Despite the variability of the reviewed research design quality, it was clearly defined that the impact of T1DM is not uniform across educational and mental variables. Strengthening the children's physical, psychological and social wellbeing is an especially important factor, as it facilitates the insulin's management as well as the learning difficulties. This is possible by supporting the parental and teacher involvement in the intervention process. This review highlights the need to reduce the distance between theory/research and practice, in some of the proposed areas in this field of knowledge.

The heritability of reading and reading-related neurocognitive components: A multi-level meta-analysis

Reading ability is a complex task requiring the integration of multiple cognitive and perceptual systems supporting language, visual and orthographic processes, working memory, attention, motor movements, and higher-level comprehension and cognition. Estimates of genetic and environmental influences for some of these reading-related neurocognitive components vary across reports. By using a multi-level meta-analysis approach, we synthesized the results of behavioral genetic research on reading-related neurocognitive components (i.e. general reading, letter-word knowledge, phonological decoding, reading comprehension, spelling, phonological awareness, rapid automatized naming, and language) of 49 twin studies spanning 4.1-18.5 years of age, with a total sample size of more than 38,000 individuals. Except for language for which shared environment seems to play a more important role, the causal architecture across most of the reading-related neurocognitive components can be represented by the following equation a² > e² > c². Moderators analysis revealed that sex and spoken language did not affect the heritability of any reading-related skills; school grade levels moderated the heritability of general reading, reading comprehension and phonological awareness.

Exploring the Influence of Early Childhood Education and Care on the Etiology of Achievement

The present study used a genetically-sensitive quantile regression approach to examine the relation between participation in early childhood education and care (ECEC) and subsequent school performance in literacy and numeracy at grades 3, 5, 7, and 9. The sample consisted of 1255 twin pairs (596 MZ; 659 DZ) with information on both ECEC and the National Assessment Program-Literacy and Numeracy (NAPLAN) scores from the Twin Study of NAPLAN. Results indicated variation in heritability estimates across the distributions of achievement, suggesting that different patterns of etiological influences may exist among children of different ability levels. Additionally, the results provided no evidence that ECEC significantly influenced achievement, and in the genetically-sensitive analyses, no evidence that ECEC moderated the influences of heritability of achievement for typically advantaged children. These results suggest that ECEC may not provide the levels of environmental support for later achievement that advocates claim, although we acknowledge that ECEC quality, which was not measured in the current study, may make a difference in whether or not ECEC influences achievement.

Is atypical rhythm a risk factor for developmental speech and language disorders?

Although a growing literature points to substantial variation in speech/language abilities related to individual differences in musical abilities, mainstream models of communication sciences and disorders have not yet incorporated these individual differences into childhood speech/language development. This article reviews three sources of evidence in a comprehensive body of research aligning with three main themes: (a) associations between musical rhythm and speech/language processing, (b) musical rhythm in children with developmental speech/language disorders and common comorbid attentional and motor disorders, and (c) individual differences in mechanisms underlying rhythm processing in infants and their relationship with later speech/language development. In light of converging evidence on associations between musical rhythm and speech/language processing, we propose the Atypical Rhythm Risk Hypothesis, which posits that individuals with atypical rhythm are at higher risk for developmental speech/language disorders. The hypothesis is framed within the larger epidemiological literature in which recent methodological advances allow for large-scale testing of shared underlying biology across clinically distinct disorders. A series of predictions for future work testing the Atypical Rhythm Risk Hypothesis are outlined. We suggest that if a significant body of evidence is found to support this hypothesis, we can envision new risk factor models that incorporate atypical rhythm to predict the risk of developing speech/language disorders. Given the high prevalence of speech/language disorders in the population and the negative long-term social and economic consequences of gaps in identifying children at-risk, these new lines of research could potentially positively impact access to early identification and treatment. This article is categorized under: Linguistics > Language in Mind and Brain Neuroscience > Development Linguistics > Language Acquisition.

Comorbidities Between Specific Learning Disorders and Psychopathology in Elementary School Children in Germany

Children with reading and/or spelling disorders have increased rates of behavioral and emotional problems and combinations of these. Some studies also find increased rates of attention-deficit/hyperactivity disorder (ADHD), conduct disorder, anxiety disorder, and depression. However, the comorbidities of, e.g., arithmetic disorders with ADHD, anxiety disorder, and depression have been addressed only rarely. The current study explored the probability of children with specific learning disorders (SLD) in reading, spelling, and/or arithmetic to also have anxiety disorder, depression, ADHD, and/or conduct disorder. The sample consisted of 3,014 German children from grades 3 and 4 (mean age 9;9 years) who completed tests assessing reading, spelling as well as arithmetic achievement and intelligence via a web-based application. Psychopathology was assessed using questionnaires filled in by the parents. In children with a SLD we found high rates of anxiety disorder (21%), depression (28%), ADHD (28%), and conduct disorder (22%). Children with SLD in multiple learning domains had a higher risk for psychopathology and had a broader spectrum of psychopathology than children with an isolated SLD. The results highlight the importance of screening for and diagnosing psychiatric comorbidities in children with SLD.

Socioeconomic Status and Reading Disability: Neuroanatomy and Plasticity in Response to Intervention

Although reading disability (RD) and socioeconomic status (SES) are independently associated with variation in reading ability and brain structure/function, the joint influence of SES and RD on neuroanatomy and/or response to intervention is unknown. In total, 65 children with RD (ages 6-9) with diverse SES were assigned to an intensive, 6-week summer reading intervention (n = 40) or to a waiting-list control group (n = 25). Before and after, all children completed standardized reading assessments and magnetic resonance imaging to measure cortical thickness. At baseline, higher SES correlated with greater vocabulary and greater cortical thickness in bilateral perisylvian and supramarginal regions-especially in left pars opercularis. Within the intervention group, lower SES was associated with both greater reading improvement and greater cortical thickening across broad, bilateral occipitotemporal and temporoparietal regions following the intervention. Additionally, treatment responders (n = 20), compared with treatment nonresponders (n = 19), exhibited significantly greater cortical thickening within similar regions. The waiting control and nonresponder groups exhibited developmentally typical, nonsignificant cortical thinning during this time period. These findings indicate that effective summer reading intervention is coupled with cortical growth, and is especially beneficial for children with RD who come from lower-SES home environments.

Cognitive Neuroscience of Dyslexia

Purpose

This review summarizes what is known about the structural and functional brain bases of dyslexia.

Method

We review the current literature on structural and functional brain differences in dyslexia. This includes evidence about differences in gray matter anatomy, white matter connectivity, and functional activations in response to print and language. We also summarize findings concerning brain plasticity in response to interventions.

Results

We highlight evidence relating brain function and structure to instructional issues such as diagnosis and prognosis. We also highlight evidence about brain differences in early childhood, before formal reading instruction in school, which supports the importance of early identification and intervention.

Conclusion

Neuroimaging studies of dyslexia reveal how the disorder is related to differences in structure and function in multiple neural circuits.

Beyond genes: A systematic review of environmental risk factors in specific reading disorder

BACKGROUND

While an understanding of the genetic contributions to specific reading disorder (RD) is emerging, there is no agreement about which putative hazard factors are clearly involved in the aetiology of this disorder.

AIMS

A literature review looking at the impact of environmental risk variables implicated in RD either per se or when interacting with the genes.

METHODS AND PROCEDURES

We performed a systematic literature review using the following keywords: dyslexia OR reading disability AND environmental risk factors OR environmental hazard factors, in the following electronic databases: PubMed, Scopus and PsycINFO, without any time restrictions.

OUTCOMES AND RESULTS

Gestational weeks and birth weight are among the pre- and peri-natal risk factors shown to reliably predict reading readiness and the odds of having RD. Inconclusive findings have been reported for maternal cigarette smoking, family history of psychiatric and medical diseases, and risk of miscarriage. A broad definition of familial socio-economic status and home literacy environment have been identified as good life-long risk predictors of reading skills.

CONCLUSIONS AND IMPLICATIONS

We highlighted the need to consider environmental hazards, their interactions and interactions with RD-candidate genes in the study of the aetiology of RD in order to provide much-needed insight into how these variables influence reading skills.

The relationship between socioeconomic status and white matter microstructure in pre-reading children: A longitudinal investigation

Reading is a learned skill crucial for educational attainment. Children from families of lower socioeconomic status (SES) tend to have poorer reading performance and this gap widens across years of schooling. Reading relies on the orchestration of multiple neural systems integrated via specific white-matter pathways, but there is limited understanding about whether these pathways relate differentially to reading performance depending on SES background. Kindergarten white-matter FA and second-grade reading outcomes were investigated in an SES-diverse sample of 125 children. The three left-hemisphere white-matter tracts most associated with reading, and their right-hemisphere homologs, were examined: arcuate fasciculus (AF), superior longitudinal fasciculus (SLF), and inferior longitudinal fasciculus (ILF). There was a significant and positive association between SES and fractional anisotropy (FA) in the bilateral ILF in kindergarten. SES moderated the association between kindergarten ILF and second grade reading performance, such that it was positive in lower-SES children, but not significant in higher-SES children. These results have implications for understanding the role of the environment in the development of the neural pathways that support reading.

Genetic and Environmental Influences on Achievement Outcomes Based on Family History of Learning Disabilities Status

A risk to develop a learning disability has been shown to run in families. Having a positive family history of learning disability seems to account for mean differences in achievement outcomes (reading, math) in that children with a positive family history score significantly lower compared to their peers with no such family history. However, the role of family history status in explaining etiological (genetic and environmental) differences among these subgroups of children has yet to be established. The present study of 872 twins (M_age = 13.30, SD_age = 1.40) from the Florida Twin Project on Reading, Behavior, and Environment utilized a multigroup approach to examine etiological differences on reading, spelling, and math among two subgroups defined by family history status. Results showed significant mean differences on all achievement outcomes, aside from math; however, no significant etiological differences on any achievement outcome were found among the two subgroups. Results support previous literature that the risk for developing a learning disability is transmitted through a family, but this is seemingly not manifested by differential etiology.

Genetic variation interacts with experience to determine interindividual differences in learned song

Learning reflects the influence of experience on genetically determined circuitry, but little is known about how experience and genetics interact to determine complex learned phenotypes. Here, we used vocal learning in songbirds to study how experience and genetics contribute to interindividual differences in learned song. Previous work has established that such differences in song within a species depend on learning, but in principle some of these differences could also depend on genetic variation. We focused on song tempo, a learned and quantifiable feature that is controlled by central neural circuitry. To identify genetic contributions to tempo we computer-tutored juvenile Bengalese finches (Lonchura striata domestica) from different genetic backgrounds with synthetic songs in which tempo was systematically varied. Computer-tutored birds exhibited unexpectedly strong heritability for song tempo and comparatively weak influence of experience. We then tested whether heritability was fixed and independent of experience by providing a second group of birds with enriched instruction via live social tutoring. Live tutoring resulted in not only a significant increase in the influence of experience on tempo but also a dramatic decrease in the influence of genetics, indicating that enriched instruction could overcome genetic biases evident under computer tutoring. Our results reveal strong heritable genetic contributions to interindividual variation in song tempo but that the degree of heritability depends profoundly on the quality of instruction. They suggest that for more complex learned phenotypes, where it can be difficult to identify and control relevant experiential variables, heritability may similarly be contingent on the specifics of experience.

Examining the Etiology of Reading Disability as Conceptualized by the Hybrid Model

A fairly recent definition of reading disability (RD) is that in the form of a hybrid model. The model views RD as a latent construct that is manifested through various observable unexpected impairments in reading related skills and through inadequate response to intervention. The current report evaluated this new conceptualization of RD from an etiological perspective. The sample consisted of 2737 twin pairs in first through fourth grade (M_age = 8.52) from the Florida Twin Project on Reading. Using twin analyses, results showed that a substantial proportion of genetic variance, a small proportion of shared environmental, and a small proportion of non-shared environmental variance was attributed to the RD factor. Findings suggest that the etiological architecture of RD closely mirrors the structure of the hybrid model of RD.

Socioeconomic status and genetic influences on cognitive development

Accurate understanding of environmental moderation of genetic influences is vital to advancing the science of cognitive development as well as for designing interventions. One widely reported idea is increasing genetic influence on cognition for children raised in higher socioeconomic status (SES) families, including recent proposals that the pattern is a particularly US phenomenon. We used matched birth and school records from Florida siblings and twins born in 1994-2002 to provide the largest, most population-diverse consideration of this hypothesis to date. We found no evidence of SES moderation of genetic influence on test scores, suggesting that articulating gene-environment interactions for cognition is more complex and elusive than previously supposed.

Neuropsychology of Learning Disabilities: The Past and the Future

Over the past 50 years, research on children and adults with learning disabilities has seen significant advances. Neuropsychological research historically focused on the administration of tests sensitive to brain dysfunction to identify putative neural mechanisms underlying learning disabilities that would serve as the basis for treatment. Led by research on classifying and identifying learning disabilities, four pivotal changes in research paradigms have produced a contemporary scientific, interdisciplinary, and international understanding of these disabilities. These changes are (1) the emergence of cognitive science, (2) the development of quantitative and molecular genetics, (3) the advent of noninvasive structural and functional neuroimaging, and (4) experimental trials of interventions focused on improving academic skills and addressing comorbid conditions. Implications for practice indicate a need to move neuropsychological assessment away from a primary focus on systematic, comprehensive assessment of cognitive skills toward more targeted performance-based assessments of academic achievement, comorbid conditions, and intervention response that lead directly to evidence-based treatment plans. Future research will continue to cross disciplinary boundaries to address questions regarding the interaction of neurobiological and contextual variables, the importance of individual differences in treatment response, and an expanded research base on (a) the most severe cases, (b) older people with LDs, and (c) domains of math problem solving, reading comprehension, and written expression. (JINS, 2017, 23, 930-940).

Parents' reading history as an indicator of risk for reading difficulties

Children from families whose members have reading impairments are found to be poorer performers, take less advantage of instruction, and require more time to reach the reading level of children whose relatives are good readers. As a family's reading history may not be available, a self-report of reading abilities is used to identify children's background. In this paper, we explored the contribution of phonological, literacy, and linguistic abilities and reported parental reading abilities to predict reading achievement at the end of the school year in a Spanish sample. Children who were starting to read were assessed in a variety of oral language, phonological, and literacy tasks at the beginning and end of the school year. Parents filled out a self-report questionnaire about their reading abilities. Their answers were used to assign children to good or poor reader parent groups (GRP vs PRP). A logistic and ROC analysis were used to assess the variables' discriminative capability, considering literacy scores at the end of the year as a measure of reading achievement. GRP children obtained higher scores than PRP children did. Performance on tasks of rapid naming assessment (RAN) letters (78.6%), Word Reading (75.7%), and Deletion (75.6%) were the most accurate predictors of children's reading achievement. IPRA showed slightly lower accuracy (73.8) than did the behavioral measures and as high specificity as RAN letters (96.2%), similarly to the percentages found in previous studies. Although behavioral measures were shown as the best predictors, parents' self-reports could also provide a quick estimation of family risk of difficulties in literacy acquisition.

Genetic transmission of reading ability

Reading is the processing of written language. Family resemblance for reading (dis)ability might be due to transmission of a genetic liability or due to family environment, including cultural transmission from parents to offspring. Familial-risk studies exploring neurobehavioral precursors for dyslexia and twin studies can only speak to some of these issues, but a combined twin-family study can resolve the nature of the transmitted risk. Word-reading fluency scores of 1100 participants from 431 families (with twins, siblings and their parents) were analyzed to estimate genetic and environmental sources of variance, and to test the presence of assortative mating and cultural transmission. Results show that variation in reading ability is mainly caused by additive and non-additive genetic factors (64%). The substantial assortative mating (r_{father-mother}=0.38) has scientific and clinical implications. We conclude that parents and offspring tend to resemble each other for genetic reasons, and not due to cultural transmission.

Evaluation of results from genome-wide studies of language and reading in a novel independent dataset

Recent genome-wide association scans (GWAS) for reading and language abilities have pin-pointed promising new candidate loci. However, the potential contributions of these loci remain to be validated. In this study, we tested 17 of the most significantly associated single nucleotide polymorphisms (SNPs) from these GWAS studies (P < 10(-6) in the original studies) in a new independent population dataset from the Netherlands: known as Familial Influences on Literacy Abilities. This dataset comprised 483 children from 307 nuclear families and 505 adults (including parents of participating children), and provided adequate statistical power to detect the effects that were previously reported. The following measures of reading and language performance were collected: word reading fluency, nonword reading fluency, phonological awareness and rapid automatized naming. Two SNPs (rs12636438 and rs7187223) were associated with performance in multivariate and univariate testing, but these did not remain significant after correction for multiple testing. Another SNP (rs482700) was only nominally associated in the multivariate test. For the rest of the SNPs, we did not find supportive evidence of association. The findings may reflect differences between our study and the previous investigations with respect to the language of testing, the exact tests used and the recruitment criteria. Alternatively, most of the prior reported associations may have been false positives. A larger scale GWAS meta-analysis than those previously performed will likely be required to obtain robust insights into the genomic architecture underlying reading and language.

Neurobiological bases of reading disorder Part I: Etiological investigations

While many studies have focused on identifying the neural and behavioral characteristics of decoding-based reading disorder (RD, aka developmental dyslexia), the etiology of RD remains largely unknown and understudied. Because the brain plays an intermediate role between genetic factors and behavioral outcomes, it is promising to address causality from a neural perspective. In the current, Part I of the two-part review, we discuss neuroimaging approaches to addressing the causality issue and review the results of studies that have employed these approaches. We assume that if a neural signature were associated with RD etiology, it would (a) manifest across comparisons in different languages, (b) be experience independent and appear in comparisons between RD and reading-matched controls, (c) be present both pre- and post-intervention, (d) be found in at-risk, pre-reading children and (e) be associated with genetic risk. We discuss each of these five characteristics in turn and summarize the studies that have examined each of them. The available literature provides evidence that anomalies in left temporo-parietal cortex, and possibly occipito-temporal cortex, may be closely related to the etiology of RD. Improved understanding of the etiology of RD can help improve the accuracy of early detection and enable targeted intervention of cognitive processes that are amenable to change, leading to improved outcomes in at-risk or affected populations.

Complex effects of dyslexia risk factors account for ADHD traits: evidence from two independent samples

BACKGROUND

Developmental dyslexia (DD) and attention deficit/hyperactivity disorder (ADHD) are among the most common neurodevelopmental disorders, whose etiology involves multiple risk factors. DD and ADHD co-occur in the same individuals much more often than would be expected by chance. Several studies have found significant bivariate heritability, and specific genes associated with either DD or ADHD have been investigated for association in the other disorder. Moreover, there are likely to be gene-by-gene and gene-by-environment interaction effects (G × G and G × E, respectively) underlying the comorbidity between DD and ADHD. We investigated the pleiotropic effects of 19 SNPs spanning five DD genes (DYX1C1, DCDC2, KIAA0319, ROBO1, and GRIN2B) and seven DD environmental factors (smoke, miscarriage, birth weight, breastfeeding, parental age, socioeconomic status, and parental education) for main, either (a) genetic or (b) environmental, (c) G × G, and (d) G × E upon inattention and hyperactivity/impulsivity. We then attempted replication of these findings in an independent twin cohort.

METHODS

Marker-trait association was analyzed by implementing the Quantitative Transmission Disequilibrium Test (QTDT). Environmental associations were tested by partial correlations. G × G were investigated by a general linear model equation and a family-based association test. G × E were analyzed through a general test for G × E in sib pair-based association analysis of quantitative traits.

RESULTS

DCDC2-rs793862 was associated with hyperactivity/impulsivity via G × G (KIAA0319) and G × E (miscarriage). Smoke was significantly correlated with hyperactivity/impulsivity. We replicated the DCDC2 × KIAA0319 interaction upon hyperactivity/impulsivity in the twin cohort.

CONCLUSIONS

DD genetic (DCDC2) and environmental factors (smoke and miscarriage) underlie ADHD traits supporting a potential pleiotropic effect.

Auditory brainstem responses to stop consonants predict literacy

OBJECTIVE

Precise temporal coding of speech plays a pivotal role in sound processing throughout the central auditory system, which, in turn, influences literacy acquisition. The current study tests whether an electrophysiological measure of this precision predicts literacy skills.

METHODS

Complex auditory brainstem responses were analysed from 62 native German-speaking children aged 11-13years. We employed the cross-phaseogram approach to compute the quality of the electrophysiological stimulus contrast [da] and [ba]. Phase shifts were expected to vary with literacy.

RESULTS

Receiver operating curves demonstrated a feasible sensitivity and specificity of the electrophysiological measure. A multiple regression analysis resulted in a significant prediction of literacy by delta cross-phase as well as phonological awareness. A further commonality analysis separated a unique variance that was explained by the physiological measure, from a unique variance that was explained by the behavioral measure, and common effects of both.

CONCLUSIONS

Despite multicollinearities between literacy, phonological awareness, and subcortical differentiation of stop consonants, a combined assessment of behavior and physiology strongly increases the ability to predict literacy skills.

SIGNIFICANCE

The strong link between the neurophysiological signature of sound encoding and literacy outcome suggests that the delta cross-phase could indicate the risk of dyslexia and thereby complement subjective psychometric measures for early diagnoses.

Descriptive epidemiology of prenatal and perinatal risk factors in a Chinese population with reading disorder

Several prenatal and perinatal factors have been found to be associated with developmental dyslexia (reading disorder) in alphabetic language. Given the absence of relevant studies of Chinese children, the present study tries to investigate these risk factors. A total of 45,850 students were recruited from grades three to six, from seven cities of Hubei province. Dyslexia in Chinese was diagnosed based on children’s clinical symptoms. The clinical symptoms of children’s reading performance were assessed by Dyslexia Checklist for Chinese Children (DCCC) and Pupil Rating Scale Revised Screening for Learning Disabilities (PRS) which were completed by parent/guardian and header teacher respectively. Chinese language exam was used to screen children with poor reading capacity. Questionnaires about prenatal and perinatal factors were completed by parent or guardian. Among the 34,748 eligible participants, 1,200 (3.45%) were diagnosed with dyslexia in Chinese. More boys suffered from dyslexia than the girls and the gender ratio was 3:1. Family history of neuropsychiatric diseases, maternal infectious diseases, difficult vaginal delivery, preterm birth, and neonatal asphyxia were found to increase the risk of developmental dyslexia in China. Closer longitudinal developmental monitoring and preventive measures should be taken for high risk children.

Cross-Study Differences in the Etiology of Reading Comprehension: a Meta-Analytical Review of Twin Studies

Numerous twin studies have examined the genetic and environmental etiology of reading comprehension, though it is likely that etiological estimates are influenced by unidentified sample conditions (e.g. Tucker-Drob and Bates, Psychol Sci:0956797615612727, 2015). The purpose of this meta-analysis was to average the etiological influences of reading comprehension and to explore the potential moderators influencing these estimates. Results revealed an average heritability estimate of h² = 0.59, with significant variation in estimates across studies, suggesting potential moderation. Moderation results indicated publication year, grade level, project, zygosity methods, and response type moderated heritability estimates. The average shared environmental estimate was c² = 0.16, with publication year, grade and zygosity methods acting as significant moderators. These findings support the role of genetics on reading comprehension, and a small significant role of shared environmental influences. The results suggest that our interpretation of how genes and environments influence reading comprehension should reflect aspects of study and sample.

NRSN1 associated grey matter volume of the visual word form area reveals dyslexia before school

Literacy learning depends on the flexibility of the human brain to reconfigure itself in response to environmental influences. At the same time, literacy and disorders of literacy acquisition are heritable and thus to some degree genetically predetermined. Here we used a multivariate non-parametric genetic model to relate literacy-associated genetic variants to grey and white matter volumes derived by voxel-based morphometry in a cohort of 141 children. Subsequently, a sample of 34 children attending grades 4 to 8, and another sample of 20 children, longitudinally followed from kindergarten to first grade, were classified as dyslexics and controls using linear binary support vector machines. The NRSN1-associated grey matter volume of the 'visual word form area' achieved a classification accuracy of ~ 73% in literacy-experienced students and distinguished between later dyslexic individuals and controls with an accuracy of 75% at kindergarten age. These findings suggest that the cortical plasticity of a region vital for literacy might be genetically modulated, thereby potentially preconstraining literacy outcome. Accordingly, these results could pave the way for identifying and treating the most common learning disorder before it manifests itself in school.