Genetic and environmental risk factors for developmental dyslexia in children: systematic review of the last decade

Searching the underlying mechanisms of specific learning disorder: An emotion recognition and social cognition aspect for Turkish clinical youth population

This study aimed to investigate impairments in social cognition in youth with specific learning disorder (SLD) through a cross sectional study. Eighty six adolescents which include of 43 SLD and 43 typically developing (TD) children completed a battery of tests to analyze social cognition, emotional process and clinical psychopathological profile. SLD group performed significantly worse than healthy controls in facial ER total accuracy score (Cohen d = .77) and Stroop interference (Cohen d = .92). In individual emotion analyses, patients with SLD have a very high deficiency in recognition of angry faces (Cohen d = .89). Between-group difference was also significant for Stroop congruent and facilitation scores (Cohen d = .99). The Specific Learning Disorder Symptom Check List-Parent Form scores were significant -and only- predictor of the model which for total accuracy score of facial recognition. The results of this study supported an impairment in emotion recognition and executive functions in adolescents with SLD but causality seems still unclear.

Are Communication Skills, Emotion Regulation and Theory of Mind Skills Impaired in Adolescents with Developmental Dyslexia?

This study investigates pragmatic language impairment, Theory of Mind (ToM), and emotion regulation in adolescents with Developmental Dyslexia(DD). The Social Responsiveness Scale-2(SRS) and Children's Communication Checklist-2(CCC-2) scores were found to be statistically significantly higher in the DD group than in healthy controls. DD group had lower performance in ToM skills and they have more difficulties in emotion regulation. We also found that CCC-2 and ToM scores were significantly correlated in adolescents with DD. These results may be important in understanding the difficulties experienced in social functioning and interpersonal relationships in adolescents with DD.

Developmental Dyslexia: Insights from EEG-Based Findings and Molecular Signatures-A Pilot Study

Developmental dyslexia (DD) is a learning disorder. Although risk genes have been identified, environmental factors, and particularly stress arising from constant difficulties, have been associated with the occurrence of DD by affecting brain plasticity and function, especially during critical neurodevelopmental stages. In this work, electroencephalogram (EEG) findings were coupled with the genetic and epigenetic molecular signatures of individuals with DD and matched controls. Specifically, we investigated the genetic and epigenetic correlates of key stress-associated genes (NR3C1, NR3C2, FKBP5, GILZ, SLC6A4) with psychological characteristics (depression, anxiety, and stress) often included in DD diagnostic criteria, as well as with brain EEG findings. We paired the observed brain rhythms with the expression levels of stress-related genes, investigated the epigenetic profile of the stress regulator glucocorticoid receptor (GR) and correlated such indices with demographic findings. This study presents a new interdisciplinary approach and findings that support the idea that stress, attributed to the demands of the school environment, may act as a contributing factor in the occurrence of the DD phenotype.

Reading and writing difficulties in third- and sixth-grade students: a cross-sectional survey

BACKGROUND

In Southern Italy and, specifically, in the region of Campania, many surveys show that the average of students with reading difficulties is much higher than in northern Italy and abroad. On the other hand, specific learning disorders (SLDs) in Campania are much less certified. Since there are no etiological reasons that can explain this apparent inconsistency, an objective of this cross-sectional study was to evaluate the extent of reading/writing difficulties in students from a province of Campania and then to assess the ability of teachers to identify such difficulties in their students.

METHODS

Of a total of 241 enrolled students, 155 (64.31%), including 73 from primary school and 82 from secondary school, belonging to 5 schools in the province of Salerno (Italy), took part in the survey. Students' reading and writing skills were assessed through standardized tests. The tests results were then compared with teacher judgments and context-related variables.

RESULTS

At the reading test, 28.7% of primary school and 13.4% of lower secondary school students fell below the 5th percentile for age. Results of the writing test were even more significant: almost half of the students of both levels of education performed below the 5th percentile. Teacher judgments showed higher agreement with standardized assessments in primary (88%, K of Cohen=0.68) than in secondary school (78%, K=0.23).

CONCLUSIONS

Reading and writing difficulties were common in our sample. While reading skills tended to improve with age, writing difficulties apparently persisted to some extent in third and sixth-grade classes. The accuracy of teacher judgments on reading skills is relatively high, but teachers seem to hardly report reading difficulties "requiring attention." Although less "severe" than others, such difficulties should be considered, mainly because of their potential developmental trajectories.

Home reading environment, sociometric and demographic factors associated with dyslexia in primary school students in China: A case-control study

Background

Developmental dyslexia (DD) has been generally recognized as a multifactorial psychological disorder in recent decades. However, studies on reading and learning environment, social and demographic factors affecting Chinese developmental dyslexia (DD) are still scarce in China. This study aims to explore multidimensional home influencing factors associated with DD before and after birth.

Methods

A total of 60 dyslexic and 252 normal elementary school students graded 2-5 were recruited in Shantou, China. The Least Absolute Shrinkage and Selection Operator (LASSO) regression model was used for the social and demographic variables screening. Odds ratios (ORs) with 95 % confidence intervals (CIs) for associations between DD and related factors were estimated by multivariate logistic regression models.

Results

Through LASSO regression, we ultimately identified 13 key variables, including maternal education level and family monthly income, among others. The logistic regression analyses showed that the risk of DD was higher in children with lower maternal education levels. Divergent parenting styles may be a risk factor for developing DD as opposed to consistent parenting styles (OR = 4.93, 95%CI: 1.11-21.91). Children whose mothers suffered from malnutrition during pregnancy were more likely to develop DD (OR = 10.31, 95%CI: 1.84-37.86), as well as exposure to second-hand smoking at home every day (OR = 5.33, 95%CI: 1.52-18.66). Interestingly, children's active reading (OR = 0.26, 95%CI: 0.08-0.84; OR = 0.17, 95%CI: 0.04-0.76 for "sometimes" and "often" compared to none, respectively), children having extracurricular reading fairy tale books (OR = 0.37, 95%CI: 0.15-0.90), and children having extracurricular reading composition books (OR = 0.25, 95%CI: 0.09-0.69) were significant protective factors for DD.

Conclusions

Home reading environment, several educational, sociometric and demographic factors may influence the development of dyslexia. We should pay attention to these factors on the development of dyslexia, so as to provide the well social and familial environment to ensure the healthy development of children.

Developmental learning disorders in children with prenatal/perinatal exposure to hypoxia: A systematic review protocol

BACKGROUND

Developmental learning disorder (DLD) belongs to neurodevelopmental disorders because it results from the developmental neurodiversity of the brain. The main causes of DLD are genetics, but environmental factors, like inadequate supply of oxygen during pregnancy or labor, are considered.

METHODS

Our search strategy will consist of electronic databases (PubMed, PsycINFO, Web of Science, EMBASE, and Cochrane Library) and hand searching. The observational studies including cohort and case-control studies will be included. The primary outcome will be (DLD). Screening and eligibility will be done independently by two reviewers based on pre-specified eligibility criteria. Data extraction will be based on a pre-pilot data extraction form, and conducted by two authors independently. Study quality will be assessed by two authors independently. Any discrepancies identified at any stage of the review will be resolved by discussion or/and consultation with another reviewer. We plan a narrative and tabular summary of the findings.

DISCUSSION

This systematic review of aetiology follows the traditional approach to evidence-based healthcare. This secondary research will assess the association between hypoxia and DLD by assessing the relationship of health-related event and outcome and examining the association between them. This review can provide information for healthcare professionals and policymakers indicating whether taking into account information about hypoxia should be permanently included in the diagnostic ontogenetic interview in the process of diagnosing neurodevelopmental disorders.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO: CRD42022371387.

Dyslexia and Stuttering: An Overview of Processing Deficits and the Relationship Between Them

Stuttering and dyslexia are two processing deficits that have an impact on a person's social and academic lives, especially as they usually affect the pediatric population more than adults. Even though they affect different domains, they have similar characteristics in their pathogenesis, epidemiology, and impact on life. Both disorders represent a considerable percentage of the population worldwide and locally in Saudi Arabia, and they have similar epidemiological trends. Family history, genetic factors, early fetal and neonatal factors, and environmental factors are all identified as risk factors for both conditions. Moreover, it has been established that both diseases share a common genetic and anatomical basis, along with a mutual disruption of diadochokinetic skills. While rehabilitative techniques can be used in both conditions, stuttering could also benefit from pharmacological interventions. This review emphasizes that extensive research should be done to explore both of these conditions as they impact different areas of one's life and the relationship between them to better understand their pathophysiological origins.

A network approach to dyslexia: Mapping the reading network

Research on the etiology of dyslexia typically uses an approach based on a single core deficit, failing to understand how variations in combinations of factors contribute to reading development and how this combination relates to intervention outcome. To fill this gap, this study explored links between 28 cognitive, environmental, and demographic variables related to dyslexia by employing a network analysis using a large clinical database of 1,257 elementary school children. We found two highly connected subparts in the network: one comprising reading fluency and accuracy measures, and one comprising intelligence-related measures. Interestingly, phoneme awareness was functionally related to the controlled and accurate processing of letter-speech sound mappings, whereas rapid automatized naming was more functionally related to the automated convergence of visual and speech information. We found evidence for the contribution of a variety of factors to (a)typical reading development, though associated with different aspects of the reading process. As such, our results contradict prevailing claims that dyslexia is caused by a single core deficit. This study shows how the network approach to psychopathology can be used to study complex interactions within the reading network and discusses future directions for more personalized interventions.

Precision Medicine as a New Frontier in Speech-Language Pathology: How Applying Insights From Behavior Genomics Can Improve Outcomes in Communication Disorders

PURPOSE

Precision medicine is an emerging intervention paradigm that leverages knowledge of risk factors such as genotypes, lifestyle, and environment toward proactive and personalized interventions. Regarding genetic risk factors, examples of interventions informed by the field of medical genomics are pharmacological interventions tailored to an individual's genotype and anticipatory guidance for children whose hearing impairment is predicted to be progressive. Here, we show how principles of precision medicine and insights from behavior genomics have relevance for novel management strategies of behaviorally expressed disorders, especially disorders of spoken language.

METHOD

This tutorial presents an overview of precision medicine, medical genomics, and behavior genomics; case examples of improved outcomes; and strategic goals toward enhancing clinical practice.

RESULTS

Speech-language pathologists (SLPs) see individuals with various communication disorders due to genetic variants. Ways of using insights from behavior genomics and implementing principles of precision medicine include recognizing early signs of undiagnosed genetic disorders in an individual's communication patterns, making appropriate referrals to genetics professionals, and incorporating genetic findings into management plans. Patients benefit from a genetics diagnosis by gaining a deeper and more prognostic understanding of their condition, obtaining more precisely targeted interventions, and learning about their recurrence risks.

CONCLUSIONS

SLPs can achieve improved outcomes by expanding their purview to include genetics. To drive this new interdisciplinary framework forward, goals should include systematic training in clinical genetics for SLPs, enhanced understanding of genotype-phenotype associations, leveraging insights from animal models, optimizing interprofessional team efforts, and developing novel proactive and personalized interventions.

Maternal age at childbirth and the risk of attention-deficit/hyperactivity disorder and learning disability in offspring

Background

Studies have shown that young maternal age at childbirth can increase the risk of attention-deficit/hyperactivity disorder (ADHD) in offspring, but a study of the U.S. population has not been reported. Moreover, there is no reported research on young and advanced maternal age at childbirth and whether it can contribute to the risk of learning disability (LD) in offspring.

Methods

This study evaluated the association between young and advanced maternal age at childbirth and offspring risk of ADHD and LD in the U.S. population. Using data from 8,098 participants included in the National Health and Nutrition Examination Survey (NHANES) conducted in 1999-2004, we analyzed the association between maternal age at childbirth and ADHD and LD risk in offspring. Odds ratios (ORs) and 95% confidence intervals (CIs) for maternal age at childbirth in association with ADHD and LD risk in offspring were estimated using multivariate logistic regression models after adjustment for age, sex, race, body mass index (BMI), poverty income ratio, smoking status during pregnancy, and NHANES cycle. Restricted cubic spline (RCS) models were used to evaluate potential non-linear relationships. Sensitivity analyses were performed to ensure the reliability of the results.

Results

Among all participants, the offspring of subjects with a maternal age at childbirth of 18-24 years had an increased risk of ADHD (OR = 1.34, 95% CI: 1.01, 1.79) and LD (OR = 1.36, 95% CI: 1.06, 1.79) or either ADHD or LD (OR = 1.48, 95% CI: 1.20, 1.81). Additionally, compared with subjects with a maternal age at childbirth of 25-29 years, subjects with a maternal age at childbirth of 35-39 years had lower odds of having offspring with ADHD (OR = 0.60, 95% CI: 0.36, 1.00) and higher odds of having offspring with LD (OR = 1.34, 95% CI: 1.01, 1.78). The relationship between maternal age at childbirth and LD risk presented a U-shaped curve.

Conclusions

These results provide epidemiological evidence showing that young and advanced maternal age at childbirth are associated with ADHD and LD risk.

Understanding Mental Health in Developmental Dyslexia: A Scoping Review

Children with dyslexia are at elevated risk of internalising and externalising mental health concerns. Our aim was to scope the extent and nature of the literature investigating factors which may influence this association. We systematically searched the peer-reviewed and grey literature with no restrictions on the date. We included both qualitative and quantitative studies. Inclusion criteria included: (1) a focus on childhood (≤18 years) reading/learning difficulties; (2) internalising and/or externalising symptoms; and (3) a potentially modifiable third factor (e.g., self-esteem). Ninety-eight studies met the inclusion criteria. We organised the studies according to individual, family, and community-level third factors. Whilst a range of third factors were identified, relatively few researchers tested associations between the third factor and mental health in the context of dyslexia. Furthermore, there was a focus on primary rather than secondary school experience and a reliance, in many cases, on teacher/parent perspectives on children's mental health. Future researchers are encouraged to explore links between socio-emotional skills, coping strategies, school connectedness, and mental health in the context of dyslexia. Research of this nature is important to assist with the identification of children who are more (or less) at risk of mental health concerns and to inform tailored mental health programs for children with dyslexia.

Experiences of parents and stakeholders in caring for, and supporting children with special needs in Ghana

We studied the caring, parenting, and support services for children with special needs in Ghana. Many of the study participants reported re-adjusting their lives in virtually every domain-social, economic, and emotional to deal with and manage the new realities. How parents navigate this space varied considerably from setting to setting. Regardless of individual and interpersonal resources, community, institutional, and policy circumstances seemed to exacerbate notions of disability. In many instances, parents had a low depth of suspicion about the precursors to disabling events in their children. Parents are constantly pursuing health care, including a cure for their children with disabilities. Views about "otherness" were noted, and these tended to undermine medical interpretations/explanations of disability generally, which in turn affected formal education and health-seeking for children. Institutional arrangements exist to encourage parents to invest in their children regardless of their perceived abilities. However, these do not seem to be sufficient, particularly for health and formal education. Programming and policy implications are highlighted.

The Detection of Early Reading Performance and Its Relationship with Biopsychosocial Risk Factors in the Study of Learning Difficulties

The study of the multiple processes involved in learning how to read can contribute towards the early detection of good and bad readers. However, it is necessary to take into consideration different biopsychosocial risk factors (pre- and perigestational, neonatal, medical, developmental and family-related) that may have a significant impact on neurodevelopment, producing atypical cognitive development that could lead to the presence of reading difficulties. The objective of this study was to identify the main psycholinguistic abilities involved in the early reading performance and analyse their relationship to biopsychosocial risk factors. A total of 110 subjects between the ages of 4 and 7 years old and enrolled in state-run schools in Spain participated in the study. Significant correlations were found between different psycholinguistic abilities and certain biopsychosocial risk factors (having had hyperbilirubinemia, having obtained a score lower than 9 on the Apgar test, having had language problems or a sibling with dyslexia). This relationship should be taken into account in the study of learning difficulties as a potential indicator to predict later reading development and even the presence of developmental dyslexia.

Building a framework to understand and address vulnerability to reading difficulties among children in schools in the United States

This paper presents a vulnerability framework as a means to contextualize inequities in reading achievement among children who are vulnerable to poor reading outcomes. Models to understand vulnerability have been applied in the social sciences and public health to identify population disparities and design interventions to improve outcomes. Vulnerability is multifaceted and governed by context. Using a vulnerability framework for the science of reading provides an innovative approach for acknowledging multilevel factors contributing to disparities. The ecological considerations of both individual differences in learners and conditions within and outside of schools ensures that scientific advances are realized for learners who are more vulnerable to experiencing reading difficulty in school.

The epidemiological evidence linking exposure to ambient particulate matter with neurodevelopmental disorders: A systematic review and meta-analysis

BACKGROUND

There has been increasing attention on the associations between ambient particulate matter (PM) in early-life and neurodevelopmental disorders (NDDs). However, the associations remained unclear when considering different types of NDDs and different sizes of PM, and vulnerable exposure windows during early-life were not identified yet.

OBJECTIVE

To synthesize the published literature on the associations between ambient particulate matter (PM) and risk of different types of neurodevelopmental disorders (NDDs) in a systematic review and meta-analysis.

METHODS

A systematic search of Medline, Embase, PubMed, Cochrane Library, and Web of Science was performed from inception through 24 January 2022. Two reviewers conducted the study selection, data extraction, and quality appraisal. A random-effects model was used for meta-analyses with two quality-of-evidence assessments (the Grading of Recommendations Assessment, Development, and Evaluation system and the best evidence synthesis system).

RESULTS

A total of 6554 articles were screened, of which 31 were included in the review, and 20 provided adequate data for meta-analyses. Exposures to particulate matter of 2.5 μm or less (PM_2.5) during prenatal periods (OR, 1.32 [95%CI, 1.03-1.69]), the first year after birth (OR, 1.62 [95%CI, 1.22-2.15]) and the second year after birth (OR, 3.13 [95%CI, 1.47-6.67]) were associated with increased risk of autism spectrum disorders (ASD) in children. The quality of evidence for these associations during early postnatal periods was somewhat moderate with limited studies. We found inconsistent evidence when considering other types of NDDs and different sizes of PM.

CONCLUSIONS AND RELEVANCE

Current evidence indicated that there might be an association between PM_2.5 exposure and higher risk of ASD, and early postnatal periods appeared to be the critical exposure window. High-quality studies are needed to assess the evidence for other types of NDDs.

Remote Digital Psychiatry for Mobile Mental Health Assessment and Therapy: MindLogger Platform Development Study

Background

Universal access to assessment and treatment of mental health and learning disorders remains a significant and unmet need. There are many people without access to care because of economic, geographic, and cultural barriers, as well as the limited availability of clinical experts who could help advance our understanding and treatment of mental health.

Objective

This study aims to create an open, configurable software platform to build clinical measures, mobile assessments, tasks, and interventions without programming expertise. Specifically, our primary requirements include an administrator interface for creating and scheduling recurring and customized questionnaires where end users receive and respond to scheduled notifications via an iOS or Android app on a mobile device. Such a platform would help relieve overwhelmed health systems and empower remote and disadvantaged subgroups in need of accurate and effective information, assessment, and care. This platform has the potential to advance scientific research by supporting the collection of data with instruments tailored to specific scientific questions from large, distributed, and diverse populations.

Methods

We searched for products that satisfy these requirements. We designed and developed a new software platform called MindLogger, which exceeds the requirements. To demonstrate the platform’s configurability, we built multiple applets (collections of activities) within the MindLogger mobile app and deployed several of them, including a comprehensive set of assessments underway in a large-scale, longitudinal mental health study.

Results

Of the hundreds of products we researched, we found 10 that met our primary requirements with 4 that support end-to-end encryption, 2 that enable restricted access to individual users’ data, 1 that provides open-source software, and none that satisfy all three. We compared features related to information presentation and data capture capabilities; privacy and security; and access to the product, code, and data. We successfully built MindLogger mobile and web applications, as well as web browser–based tools for building and editing new applets and for administering them to end users. MindLogger has end-to-end encryption, enables restricted access, is open source, and supports a variety of data collection features. One applet is currently collecting data from children and adolescents in our mental health study, and other applets are in different stages of testing and deployment for use in clinical and research settings.

Conclusions

We demonstrated the flexibility and applicability of the MindLogger platform through its deployment in a large-scale, longitudinal, mobile mental health study and by building a variety of other mental health–related applets. With this release, we encourage a broad range of users to apply the MindLogger platform to create and test applets to advance health care and scientific research. We hope that increasing the availability of applets designed to assess and administer interventions will facilitate access to health care in the general 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.

Learning Disabilities in Reading and Writing and Type of Delivery in Twin Births

The aim of this study was to analyse the relationship between the type of delivery (vaginal or caesarean), as a risk factor, and the likelihood of having learning disabilities in reading (reading accuracy) and writing (phonetic and visual orthography), controlling for the interaction and/or confounding effect of gestational, obstetric, and neonatal variables (maternal age at delivery, gestational age, foetal presentation, Apgar 1, and newborn weight) among six-year-old children born in twin births. In this retrospective cohort study, the exposed and non-exposed cohorts consisted of children born by caesarean section and vaginal delivery, respectively. A total of 124 children born in twin births were evaluated in year one of primary education. Intelligence was measured using the K-BIT test; reading and writing variables were evaluated using the Evalúa-1 battery of tests, and clinical records were used to measure gestational, obstetric, and neonatal variables. Binary logistic regressions applied to each dependent variable indicated that caesarean delivery is a possible independent risk factor for difficulties in reading accuracy and phonetic and visual orthography. Future research using larger samples of younger children is required to analyse the relationship between obstetric and neonatal variables and the different basic indicators of reading and writing.

A systematic review and meta-analysis of imaging genetics studies of specific reading disorder

The imaging genetics of specific reading disabilities (SRD) is an emerging field that aims to characterize the disabilities' neurobiological causes, including atypical brain structure and function and distinct genetic architecture. The present review aimed to summarize current imaging genetics studies of SRD, characterize the effect sizes of reported results by calculating Cohen's d, complete a Fisher's Combined Probability Test for genes featured in multiple studies, and determine areas for future research. Results demonstrate associations between SRD risk genes and reading network brain phenotypes. The Fisher's test revealed promising results for the genes DCDC2, KIAA0319, FOXP2, SLC2A3, and ROBO1. Future research should focus on exploratory approaches to identify previously undiscovered genes. Using comprehensive neuroimaging (e.g., functional and effective connectivity) and genetic (e.g., sequencing and epigenetic) techniques, and using larger samples, diverse stages of development, and longitudinal investigations, would help researchers understand the neurobiological correlates of SRD to improve early identification.

Developmental Dyslexia: Environment Matters

Developmental dyslexia (DD) is a multifactorial, specific learning disorder. Susceptibility genes have been identified, but there is growing evidence that environmental factors, and especially stress, may act as triggering factors that determine an individual's risk of developing DD. In DD, as in most complex phenotypes, the presence of a genetic mutation fails to explain the broad phenotypic spectrum observed. Early life stress has been repeatedly associated with the risk of multifactorial disorders, due to its effects on chromatin regulation, gene expression, HPA axis function and its long-term effects on the systemic stress response. Based on recent evidence, we discuss the potential role of stress on DD occurrence, its putative epigenetic effects on the HPA axis of affected individuals, as well as the necessity of early and appropriate intervention, based on the individual stress-associated (endo)phenotype.

Genome-Wide Association Study of Motor Coordination

The ability to finely control our movement is key to achieving many of the educational milestones and life-skills we develop throughout our lives. Despite the centrality of coordination to early development, there is a vast gap in our understanding of the underlying biology. Like most complex traits, both genetics and environment influence motor coordination, however, the specific genes, early environmental risk factors and molecular pathways are unknown. Previous studies have shown that about 5% of school-age children experience unexplained difficulties with motor coordination. These children are said to have Developmental Coordination Disorder (DCD). For children with DCD, these motor coordination difficulties significantly impact their everyday life and learning. DCD is associated with poorer academic achievement, reduced quality of life, it can constrain career opportunities and increase the risk of mental health issues in adulthood. Despite the high prevalence of coordination difficulties, many children remain undiagnosed by healthcare professionals. Compounding under-diagnosis in the clinic, research into the etiology of DCD is severely underrepresented in the literature. Here we present the first genome-wide association study to examine the genetic basis of early motor coordination in the context of motor difficulties. Using data from the Avon Longitudinal Study of Parents and Children we generate a derived measure of motor coordination from four components of the Movement Assessment Battery for Children, providing an overall measure of coordination across the full range of ability. We perform the first genome-wide association analysis focused on motor coordination (N = 4542). No single nucleotide polymorphisms (SNPs) met the threshold for genome-wide significance, however, 59 SNPs showed suggestive associations. Three regions contained multiple suggestively associated SNPs, within five preliminary candidate genes: IQSEC1, LRCC1, SYNJ2B2, ADAM20, and ADAM21. Association to the gene IQSEC1 suggests a potential link to axon guidance and dendritic projection processes as a potential underlying mechanism of motor coordination difficulties. This represents an interesting potential mechanism, and whilst further validation is essential, it generates a direct window into the biology of motor coordination difficulties. This research has identified potential biological drivers of DCD, a first step towards understanding this common, yet neglected neurodevelopmental disorder.

Relationship between the order of permanent tooth eruption and the predominance of motor function laterality: a cross-sectional study

OBJECTIVES

To assess whether the order of permanent tooth eruption may be a useful indicator of motor function laterality.

METHODS

We conducted a cross-sectional study in schoolchildren aged 6-8 years old evaluated in the annual school-based routine dental health examinations conducted by the staff of the primary care centre of an urban district in Barcelona, Spain. We also evaluated hand, foot, eye, and auditory lateralities using a battery of simple exercises. Bivariate and multivariate analysis of data was performed.

RESULTS

The study sample included 388 children, 51.3% female, with a mean age of 6.5 years. Right laterality was the predominant side in every variable under study, especially in tooth eruption (310 children; 80%), handedness (349; 89.9%), and footedness (337; 86.8%). In the bivariate analysis, we found a statistically significant association of tooth eruption laterality with handedness and footedness, and of tooth eruption laterality with ocular and auditory lateralities (p<.001). In the multivariate analysis, tooth eruption laterality and foot laterality were independent variables significantly associated with hand laterality. The diagnostic accuracy of tooth eruption laterality and foot laterality in relation to hand laterality as reference, showed a similar sensitivity and positive and negative predictive values, but the specificity of dentition laterality was higher (79% versus 66%).

CONCLUSIONS

Laterality in the order of dental eruption is a useful indicator of right or left motor function laterality in developing individuals that may be particularly helpful to determine the main dominance in cases of crossed laterality.

Conditions requiring hospitalisations, more than general anaesthesia itself, are associated with diagnosis of learning disorders in children

BACKGROUND

Anaesthesia is neurotoxic in developing primates. Retrospective clinical studies show a correlation between exposure to anaesthesia during infancy and the occurrence of learning disorders (LD). Prospective studies failed to detect any influence of a single exposure to anaesthesia on neurodevelopment. We hypothesised that some specific populations of children were electively sensitive to anaesthesia-related neurotoxicity.

METHODS

Using a case-control design, we analysed the medical histories of children with LD, compared to those of their normally reading siblings. Interviews were conducted and medical records were reviewed. The numbers of hospitalisations and anaesthesia exposures before the age of five years were determined.

RESULTS

Four hundred fourteen dyslexic children were screened over a one-year period. Two hundred and seventy patients were excluded due to confounding variables (single child, all siblings showing LD or any condition placing the neurological prognosis at risk (N = 107/414 for the latter)) or inability to accurately collect evaluation criteria. In the 144 case-control pairs studied, the mean number of hospitalisations was significantly different (N = 1.097 ± 0 .135/case versus 0.667 ± 0.097/control, p = 0.0052), as was the proportion of hospitalised patients (54.2% versus 38.9%, p = 0.0031). The mean number of anaesthesia exposures per individual was not statistically different (N = 0.958 ± 0.183/case versus 0.569 ± 0.107/control, p =  0.0732), but the proportion of children anaesthetised at least once was (43.8% (cases) versus 33.3% (controls), p =  0.0301).

DISCUSSION

One or more hospitalisation(s) may reflect a health status and/or have an iatrogenic effect disrupting the normal setting up of learning abilities. Anaesthesia may play a role, but a correlation between LD and anaesthesia is of a lower magnitude than between LD and hospitalisation.

From BDNF to reading: Neural activation and phonological processing as multiple mediators

The BDNF gene is a prominent promoter of neuronal development, maturation and plasticity. Its Val⁶⁶Met polymorphism affects brain morphology and function within several areas and is associated with several cognitive functions and neurodevelopmental disorder susceptibility. Recently, it has been associated with reading, reading-related traits and altered neural activation in reading-related brain regions. However, it remains unknown if the intermediate phenotypes (IPs, such as brain activation and phonological skills) mediate the pathway from gene to reading or reading disability. By conducting a serial multiple mediation model in a sample of 94 children (age 5-13), our findings revealed no direct effects of genotype on reading. Instead, we found that genotype is associated with brain activation in reading-related and more domain general regions which in turn is associated with phonological processing which is associated with reading. These findings suggest that the BDNF-Val⁶⁶Met polymorphism is related to reading via phonological processing and functional activation. These results support brain imaging data and neurocognitive traits as viable IPs for complex behaviors.

Identifying interactive biological pathways associated with reading disability

INTRODUCTION

Past research has suggested that reading disability is a complex disorder involving genetic and environment contributions, as well as gene-gene and gene-environment interaction, but to date little is known about the underlying mechanisms.

METHOD

Using the Avon Longitudinal Study of Parents and Children, we assessed the contributions of genetic, demographic, and environmental variables on case-control status using machine learning. We investigated the functional interactions between genes using pathway and network analysis.

RESULTS

Our results support a systems approach to studying the etiology of reading disability with many genes (e.g., RAPGEF2, KIAA0319, DLC1) and biological pathways (e.g., neuron migration, positive regulation of dendrite regulation, nervous system development) interacting with each other. We found that single nucleotide variants within genes often had opposite effects and that enriched biological pathways were mediated by neuron migration. We also identified behavioral (i.e., receptive language, nonverbal intelligence, and vocabulary), demographic (i.e., mother's highest education), and environmental (i.e., birthweight) factors that influenced case-control status when accounting for genetic information.

DISCUSSION

The behavioral and demographic factors were suggested to be protective against reading disability status, while birthweight conveyed risk. We provided supporting evidence that reading disability has a complex biological and environmental etiology and that there may be a shared genetic and neurobiological architecture for reading (dis)ability.

The Reliability and Validity of an Assessment Tool for Developmental Dyslexia in Chinese Children

Developmental dyslexia (DD) is a common neurobehavioral disorder in children. It refers to the phenomenon in which children with normal intelligence lag significantly behind their peers in reading ability. In China, there is no unified standard for the assessment of dyslexia due to the use of simplified and traditional Chinese characters in different regions. This study was aimed at analyzing the reliability and validity of the self-developed Chinese dyslexia assessment tool named Chinese Reading Ability Test (CRAT), which was suitable for students of grade 3 to 5 in primary school. We randomly selected three primary schools in Shantou city of China, including two in the central district and one in the surrounding district. A total of 1492 students of grades 3 through 5 were recruited. We assessed the reliability of CRAT by test-retest reliability and internal consistency. The validity assessment was realized by discriminant validity, content validity and confirmatory factor analysis (CFA). For reliability, the test-retest correlation coefficient of the total score of the CRAT was 0.671. The difference between the test-retest was not statistically significant. The Cronbach's alpha coefficient of the CRAT was 0.75. For validity, the correlation coefficient between the score of each subscale and the total score of the scale ranged from 0.29 to 0.73. The indexes of the three structural equation models all meet the standard (p > 0.05, χ²/df < 2.00, RMSEA < 0.05, GFI > 0.90, AGFI > 0.90, NFI > 0.90, CFI > 0.90 and IFI > 0.90). The fitting effects of the models were good. The CRAT has sufficient reliability and validity which could be used for the assessment and auxiliary diagnosis of Chinese Dyslexia in primary school students of grade 3 to 5.

Funktionaler Analphabetismus in Deutschland – Größenordnung, Ursachen, Interventionen

Zusammenfassung. Allein in Deutschland verfügen etwa 7.5 Millionen Erwachsene nicht über ausreichende Lese- und Schreibkompetenzen, um in angemessener Weise am gesellschaftlichen Leben teilhaben zu können. Sie können maximal kurze, einfache Texte sinnentnehmend lesen. Diese Personen werden häufig als funktionale Analphabetinnen und Analphabeten bezeichnet. Die Arbeit gibt einen Überblick zu Größenordnung, Ursachen und Interventionsmöglichkeiten bei funktionalem Analphabetismus. Es wird ein biopsychosoziales Ursachenmodell vorgestellt, das biologische Vulnerabilitätsfaktoren postuliert, die unter ungünstigen psychosozialen Bedingungen zu einer erhöhten Wahrscheinlichkeit für die Entwicklung von Lese- und Schreibproblemen führen. Weiterhin wird auf Unterschiede zwischen und Gemeinsamkeiten von funktionalem Analphabetismus und Lese-Rechtschreib-Störung (LRS) eingegangen. Abschließend werden aktuelle Entwicklungen von Trainingsprogrammen zur Förderung der Lese- und Rechtschreibfähigkeiten von Erwachsenen, häufig im Kontext von Grundbildungsprogrammen, beschrieben.

Validity and Reliability of the Dyslexia Checklist for Chinese Children

The study on developmental dyslexia (DD) has fairly matured in the past decades, even when there is a lack of a standardized and convenient instrument for dyslexia in the Chinese population. The purpose of this study was to assess the reliability and validity of the Dyslexia Checklist for Chinese Children (DCCC), which was administered to Chinese students in primary school. A total of 545 students from grades 2 through 6 were recruited in Wuhan to participate in this study. We used confirmatory factor analysis (CFA) to evaluate the structure validity of the DCCC. Concurrent validity was determined via correlations between the DCCC and the verbal comprehension index (VCI), and Chinese achievement. The reliability of the DCCC was assessed via test-retest reliability and internal consistency. The CFA suggested that the first order model with eight factors and 55 items fit the data well (RMSEA = 0.057, CFI = 0.930, and TLI = 0.925). The DCCC was negatively associated with VCI (r = −0.218) and Chinese achievement (r = −0.372). The test-retest reliability of the DCCC was 0.734, and the internal consistency of all subscales was above 0.752. The DCCC thus proved to have adequate validity and reliability to screen Chinese dyslexia among students in grades 2 through 6.