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Pediatrics Jul 2020Dyslexia is a common learning disorder that renders children susceptible to poor health outcomes and many elements of socioeconomic difficulty. It is commonly... (Review)
Review
Dyslexia is a common learning disorder that renders children susceptible to poor health outcomes and many elements of socioeconomic difficulty. It is commonly undiagnosed until a child has repeatedly failed to learn to read in elementary school; this late diagnosis not only places the child at an academic disadvantage but also can be a precursor to psychiatric comorbidities such as anxiety and depression. Genetic and neuroimaging research have revealed that dyslexia is heritable and that it is undergirded by brain differences that are present even before reading instruction begins. Cognitive-behavioral research has revealed that there are early literacy skill deficits that represent red flags for dyslexia risk and can be measured at a preschool age. Altogether, this evidence points to dyslexia as a disorder that can be flagged by a pediatrician before school entry, during a period of heightened brain plasticity when interventions are more likely to be effective. In this review, we discuss the clinical implications of the most recent advances in dyslexia research, which converge to indicate that early identification and screening are crucial to the prevention or mitigation of adverse secondary consequences of dyslexia. We further highlight evidence-based and practical strategies for the implementation of early risk identification in pediatric practice so that physicians can be empowered in their ability to treat, educate, and advocate for their patients and families with dyslexia.
Topics: Child; Dyslexia; Early Diagnosis; Humans; Lactones; Learning; Neuroimaging; Reading; Risk Factors
PubMed: 32576595
DOI: 10.1542/peds.2019-3046 -
Nature Genetics Nov 2022Reading and writing are crucial life skills but roughly one in ten children are affected by dyslexia, which can persist into adulthood. Family studies of dyslexia...
Reading and writing are crucial life skills but roughly one in ten children are affected by dyslexia, which can persist into adulthood. Family studies of dyslexia suggest heritability up to 70%, yet few convincing genetic markers have been found. Here we performed a genome-wide association study of 51,800 adults self-reporting a dyslexia diagnosis and 1,087,070 controls and identified 42 independent genome-wide significant loci: 15 in genes linked to cognitive ability/educational attainment, and 27 new and potentially more specific to dyslexia. We validated 23 loci (13 new) in independent cohorts of Chinese and European ancestry. Genetic etiology of dyslexia was similar between sexes, and genetic covariance with many traits was found, including ambidexterity, but not neuroanatomical measures of language-related circuitry. Dyslexia polygenic scores explained up to 6% of variance in reading traits, and might in future contribute to earlier identification and remediation of dyslexia.
Topics: Child; Adult; Humans; Genome-Wide Association Study; Dyslexia; Reading; Language; Asian People
PubMed: 36266505
DOI: 10.1038/s41588-022-01192-y -
Brain and Behavior Sep 2022Among the target groups in child and adolescent psychiatry, transcranial direct current stimulation (tDCS) has been more applied in neurodevelopmental disorders... (Review)
Review
A systematic review of randomized controlled trials on efficacy and safety of transcranial direct current stimulation in major neurodevelopmental disorders: ADHD, autism, and dyslexia.
OBJECTIVE
Among the target groups in child and adolescent psychiatry, transcranial direct current stimulation (tDCS) has been more applied in neurodevelopmental disorders specifically, attention-deficit hyperactivity disorder (ADHD), autism spectrum disorder (ASD), and dyslexia. This systematic review aims to provide the latest update on published randomized-controlled trials applying tDCS in these disorders for evaluating its efficacy and safety.
METHODS
Based on a pre-registered protocol (PROSPERO: CRD42022321430) and using the PRISMA approach, a literature search identified 35 randomized controlled trials investigating the effects of tDCS on children and adolescents with ADHD (n = 17), ASD (n = 11), and dyslexia (n = 7).
RESULTS
In ADHD, prefrontal anodal tDCS is reported more effective compared to stimulation of the right inferior frontal gyrus. Similarly in ASD, prefrontal anodal tDCS was found effective for improving behavioral problems. In dyslexia, stimulating temporoparietal regions was the most common and effective protocol. In ASD and dyslexia, all tDCS studies found an improvement in at least one of the outcome variables while 64.7% of studies (11 of 17) in ADHD found a similar effect. About 88% of all tDCS studies with a multi-session design in 3 disorders (16 of 18) reported a significant improvement in one or all outcome variables after the intervention. Randomized, double-blind, controlled trials consisted of around 70.5%, 36.3%, and 57.1% of tDCS studies in ADHD, ASD, and dyslexia, respectively. tDCS was found safe with no reported serious side effects in 6587 sessions conducted on 745 children and adolescents across 35 studies.
CONCLUSION
tDCS was found safe and partially effective. For evaluation of clinical utility, larger randomized controlled trials with a double-blind design and follow-up measurements are required. Titration studies that systematically evaluate different stimulation intensities, duration, and electrode placement are lacking.
Topics: Adolescent; Attention Deficit Disorder with Hyperactivity; Autism Spectrum Disorder; Autistic Disorder; Child; Dyslexia; Humans; Prefrontal Cortex; Randomized Controlled Trials as Topic; Transcranial Direct Current Stimulation
PubMed: 35938945
DOI: 10.1002/brb3.2724 -
Pediatrics and Neonatology May 2021There is a growing interest in understanding dyslexia and the mechanisms involved in reading difficulties. Inquiries into the morphological and physiological changes of... (Review)
Review
There is a growing interest in understanding dyslexia and the mechanisms involved in reading difficulties. Inquiries into the morphological and physiological changes of the brain have contributed to our increased understanding of reading ability and dyslexia. Similarly, inquiries into brain chemistry and reading provide a neurometabolic framework of dyslexia in terms of poor reading and phonological measures. Also, studies of the genetic etiology of reading yield substantial evidence of genes and SNPs associated with dyslexia. However, little is known about the interface between these distinct areas of knowledge. Therefore, we offer an exhaustive perspective on dyslexia using the idea of modularity by assimilating the findings and implications from the brain morphological, neurophysiological, neurochemical, genetic, and educational insights into dyslexia. We contend that this endeavor will provide a beneficial foundation for aiming at the possibilities of a holistic intervention and informed solutions for reading difficulties.
Topics: Brain; Cognition; Dyslexia; Humans; Reading
PubMed: 33775610
DOI: 10.1016/j.pedneo.2021.03.001 -
Frontiers in Neuroscience 2022As some critics have stated, the term "developmental dyslexia" refers to a strictly human disorder, relating to a strictly human capacity - reading - so it cannot be... (Review)
Review
As some critics have stated, the term "developmental dyslexia" refers to a strictly human disorder, relating to a strictly human capacity - reading - so it cannot be modeled in experimental animals, much less so in lowly rodents. However, two endophenotypes associated with developmental dyslexia are eminently suitable for animal modeling: Cerebral Lateralization, as illustrated by the association between dyslexia and non-righthandedness, and Cerebrocortical Dysfunction, as illustrated by the described abnormal structural anatomy and/or physiology and functional imaging of the dyslexic cerebral cortex. This paper will provide a brief review of these two endophenotypes in human beings with developmental dyslexia and will describe the animal work done in my laboratory and that of others to try to shed light on the etiology of and neural mechanisms underlying developmental dyslexia. Some thought will also be given to future directions of the research.
PubMed: 36452335
DOI: 10.3389/fnins.2022.981801 -
Journal of Psychiatric Research Oct 2021Long-term effects of ADHD medication on cognitive functions are not well known. This study investigates development of cognitive functions and ADHD symptoms on... (Clinical Trial)
Clinical Trial
OBJECTIVE
Long-term effects of ADHD medication on cognitive functions are not well known. This study investigates development of cognitive functions and ADHD symptoms on well-controlled medication for 1 year in children and adolescents.
STUDY DESIGN
This study is part of an ongoing open uncontrolled trial of long-term medication for ADHD in children and adolescents aged 6-18 years with any form of ADHD, and frequently comorbid autism spectrum disorder (ASD, 29%) or autistic traits (24%). Other comorbidities were oppositional defiant disorder, dyslexia/language disorder, borderline intellectual functioning, developmental coordination disorder. This analysis includes 87 participants (61 boys, 26 girls) who completed Wechsler tests at baseline and after 12 months. ADHD symptoms were investigator-rated on the ADHD Rating Scale-IV at the same time points.
RESULTS
The whole group of children and adolescents showed significant improvements in Wechsler Full Scale IQ (FSIQ, mean at baseline 92.6, at 12 months 97.95), and on the Index Scales Verbal Comprehension, Working Memory and Processing Speed, after one year of well-controlled ADHD medication. Comorbid dyslexia/language impairment predicted a larger rise in FSIQ, but not gender, ADHD presentation or comorbid ASD. Robust improvements in ADHD symptoms were observed (mean ADHD-Rating Scale score at baseline 34.6, and at 12 months 18.3).
CONCLUSIONS
Cognitive test scores and ADHD symptoms were improved on well-controlled medication for 1 year in children and adolescents with ADHD, autism and other comorbidities. The main study limitation is the open uncontrolled trial design.
Topics: Adolescent; Attention Deficit Disorder with Hyperactivity; Autism Spectrum Disorder; Child; Cognition; Dyslexia; Female; Humans; Male; Wechsler Scales
PubMed: 34375772
DOI: 10.1016/j.jpsychires.2021.07.055 -
Frontiers in Public Health 2023The provisions of the United Nation's Sustainable Development Goals (SDGs) for disability-inclusive education have stimulated a growing interest in ascertaining the...
AIM
The provisions of the United Nation's Sustainable Development Goals (SDGs) for disability-inclusive education have stimulated a growing interest in ascertaining the prevalence of children with developmental disabilities globally. We aimed to systematically summarize the prevalence estimates of developmental disabilities in children and adolescents reported in systematic reviews and meta-analyses.
METHODS
For this umbrella review we searched PubMed, Scopus, Embase, PsycINFO, and Cochrane Library for systematic reviews published in English between September 2015 and August 2022. Two reviewers independently assessed study eligibility, extracted the data, and assessed risk of bias. We reported the proportion of the global prevalence estimates attributed to country income levels for specific developmental disabilities. Prevalence estimates for the selected disabilities were compared with those reported in the Global Burden of Disease (GBD) Study 2019.
RESULTS
Based on our inclusion criteria, 10 systematic reviews reporting prevalence estimates for attention-deficit/hyperactivity disorder, autism spectrum disorder, cerebral palsy, developmental intellectual disability, epilepsy, hearing loss, vision loss and developmental dyslexia were selected from 3,456 identified articles. Global prevalence estimates were derived from cohorts in high-income countries in all cases except epilepsy and were calculated from nine to 56 countries. Sensory impairments were the most prevalent disabilities (approximately 13%) and cerebral palsy was the least prevalent disability (approximately 0.2-0.3%) based on the eligible reviews. Pooled estimates for geographical regions were available for vision loss and developmental dyslexia. All studies had a moderate to high risk of bias. GBD prevalence estimates were lower for all disabilities except cerebral palsy and intellectual disability.
CONCLUSION
Available estimates from systematic reviews and meta-analyses do not provide representative evidence on the global and regional prevalence of developmental disabilities among children and adolescents due to limited geographical coverage and substantial heterogeneity in methodology across studies. Population-based data for all regions using other approaches such as reported in the GBD Study are warranted to inform global health policy and intervention.
Topics: Adolescent; Child; Humans; Autism Spectrum Disorder; Cerebral Palsy; Developmental Disabilities; Dyslexia; Epilepsy; Intellectual Disability; Prevalence; Systematic Reviews as Topic
PubMed: 36891340
DOI: 10.3389/fpubh.2023.1122009 -
Frontiers in Public Health 2022Dyslexia is a disorder characterized by an impaired ability to understand written and printed words or phrases. Epidemiological longitudinal data show that dyslexia is... (Meta-Analysis)
Meta-Analysis
Dyslexia is a disorder characterized by an impaired ability to understand written and printed words or phrases. Epidemiological longitudinal data show that dyslexia is highly prevalent, affecting 10-20% of the population regardless of gender. This study aims to provide a detailed overview of research status and development characteristics of dyslexia from types of articles, years, countries, institutions, journals, authors, author keywords, and highly cited papers. A total of 9,166 publications have been retrieved from the Social Sciences Citation Index (SSCI) and Science Citation Index Expanded (SCI-E) from 2000 to 2021. The United States of America, United Kingdom, and Germany were the top three most productive countries in terms of the number of publications. China, Israel, and Japan led the Asia research on dyslexia. University of Oxford had the most publications and won first place in terms of h-index. was the most productive journal in this field and Psychology was the most used subject category. Keywords analysis indicated that "developmental dyslexia," "phonological awareness," children and fMRI were still the main research topics. "Literacy," "rapid automatized naming (RAN)," "assessment," "intervention," "meta-analysis," "Chinese," "executive function," "morphological awareness," "decoding," "dyscalculia," "EEG," "Eye tracking," "rhythm," "bilingualism," and "functional connectivity" might become the new research hotspots.
Topics: Asia; Bibliometrics; Child; China; Dyslexia; Humans; United Kingdom; United States
PubMed: 35812514
DOI: 10.3389/fpubh.2022.915053 -
Translational Pediatrics Feb 2020Neurobiology helps us understand the processes that drive neurological processes including dyslexia. This article outlines the neurobiology underpinning typical reading... (Review)
Review
Neurobiology helps us understand the processes that drive neurological processes including dyslexia. This article outlines the neurobiology underpinning typical reading skills and those seen in dyslexia, which is characterized by problems with accurate or fluent word recognition, poor decoding, and poor spelling abilities. There are exciting new developments in the neurobiological changes resulting from educational interventions for dyslexia, though more research is needed in this regard. This article also outlines the clinical features of dyslexia across the developmental span, and provides guidance to clinicians about referral to community resources and advocacy for families to seek educational interventions. Screening and diagnostic tools are described, as are interventions for remediation and accommodations for dyslexia across the educational span.
PubMed: 32206582
DOI: 10.21037/tp.2019.09.07