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Journal of Neurology, Neurosurgery, and... Dec 2003
Topics: Adult; Child; Dyslexia; Humans
PubMed: 14638872
DOI: 10.1136/jnnp.74.12.1603 -
Medicina Mar 2023Beyond the frequent coexistence of attention deficit hyperactivity disorder (ADHD) and reading disorder (dyslexia), the present review aims to examine the available... (Review)
Review
Beyond the frequent coexistence of attention deficit hyperactivity disorder (ADHD) and reading disorder (dyslexia), the present review aims to examine the available empirical evidence on how ADHD negatively impacts on learning to read. Existing data suggest that the presence of the disorder (especially inattention symptoms), may affect i) the correct acquisition of reading, either directly or through its influence on the precursors to reading; ii) decoding skills themselves (reading accuracy and fluency), both directly and indirectly through its influence on cognitive processes such as distractibility or executive functions; and iii) reading comprehension, probably indirectly through the executive and verbal memory difficulties characteristic of ADHD. These findings have important implications for better characterizing and intervening on reading difficulties in ADHD, whether clinical or subclinical.
Topics: Humans; Attention Deficit Disorder with Hyperactivity; Comprehension; Learning; Cognition; Executive Function; Dyslexia
PubMed: 36820478
DOI: No ID Found -
Wiley Interdisciplinary Reviews.... 2016Developmental dyslexia is an unexplained inability to acquire accurate or fluent reading that affects approximately 5-17% of children. Dyslexia is associated with... (Review)
Review
Developmental dyslexia is an unexplained inability to acquire accurate or fluent reading that affects approximately 5-17% of children. Dyslexia is associated with structural and functional alterations in various brain regions that support reading. Neuroimaging studies in infants and pre-reading children suggest that these alterations predate reading instruction and reading failure, supporting the hypothesis that variant function in dyslexia susceptibility genes lead to atypical neural migration and/or axonal growth during early, most likely in utero, brain development. Yet, dyslexia is typically not diagnosed until a child has failed to learn to read as expected (usually in second grade or later). There is emerging evidence that neuroimaging measures, when combined with key behavioral measures, can enhance the accuracy of identification of dyslexia risk in pre-reading children but its sensitivity, specificity, and cost-efficiency is still unclear. Early identification of dyslexia risk carries important implications for dyslexia remediation and the amelioration of the psychosocial consequences commonly associated with reading failure.
Topics: Animals; Biomarkers; Brain; Brain Mapping; Child; Child, Preschool; Diffusion Tensor Imaging; Dyslexia; Electroencephalography; Evoked Potentials; Female; Humans; Infant; Infant, Newborn; Magnetic Resonance Imaging; Reading; Risk Factors; Speech Perception
PubMed: 26836227
DOI: 10.1002/wcs.1383 -
Revista de Neurologia Feb 2003Developmental dyslexia makes up an important proportion of the known learning disorders. Until the late 1970s most research on dyslexia was carried out by educators and... (Review)
Review
Developmental dyslexia makes up an important proportion of the known learning disorders. Until the late 1970s most research on dyslexia was carried out by educators and educational psychologists, but soon after the publication of some dyslexic cases with focal disorders of neuronal migration to the cerebral cortex, interest in the neurobiological and neurocognitive underpinnings of dyslexia grew, especially in Europe and North America. There are at least two types of developmental dyslexia--phonological and surface. Surface dyslexia refers to a disorder in which the difficulty lies in reading irregular words, whereas phonological dyslexia is characterized by difficulty with pseudowords. Phonological dyslexia is the more common of the two types. Surface dyslexia does not present a major problem in a language such as Spanish, where the number of irregular words is indeed very small. Still, in languages such as English, where irregular words are common, the phonological type of developmental dyslexia is much more common. Phonologic dyslexics have problems with phonological awareness, that is, the conscious knowledge and manipulation of speech sounds, which is the most proximate explanation for their difficulty in reading pseudowords. Many, but not all, phonologic dyslexics also have problems processing rapidly changing sounds, even if not linguistic, and some slow sounds, too. The same group tends to have visual problems, especially involving the so-called magnocellular pathway of the visual system, which, among others, has the role of analyzing movement. Accompanying these perceptual and cognitive deficits, phonologic dyslexics also show abnormal brain activation to phonological tasks, as shown in functional magnetic resonance studies (figure). In addition, dyslexic brains show focal malformations, ectopias and microgyria, of the cerebral cortex, involving mainly the left perisylvian region and the word form area in the temporo-occipital junction. There are also changes in the composition of neurons in the lateral and medial geniculate nuclei of the thalamus. Experimental studies indicate that the thalamic changes are a consequence of the focal malformations, and that they are responsible for the sound processing deficits. None of these discoveries have changed the therapeutic modalities in this condition, but it is hoped that this will be the next area of progress.
Topics: Brain; Child, Preschool; Dyslexia; Humans; Reading; Vision, Ocular
PubMed: 12599096
DOI: No ID Found -
BMC Medical Genomics Sep 2023Attention deficit hyperactivity disorder (ADHD) is commonly associated with developmental dyslexia (DD), which are both prevalent and complicated pediatric...
BACKGROUND
Attention deficit hyperactivity disorder (ADHD) is commonly associated with developmental dyslexia (DD), which are both prevalent and complicated pediatric neurodevelopmental disorders that have a significant influence on children's learning and development. Clinically, the comorbidity incidence of DD and ADHD is between 25 and 48%. Children with DD and ADHD may have more severe cognitive deficiencies, a poorer level of schooling, and a higher risk of social and emotional management disorders. Furthermore, patients with this comorbidity are frequently treated for a single condition in clinical settings, and the therapeutic outcome is poor. The development of effective treatment approaches against these diseases is complicated by their comorbidity features. This is often a major problem in diagnosis and treatment. In this study, we developed bioinformatical methodology for the analysis of the comorbidity of these two diseases. As such, the search for candidate genes related to the comorbid conditions of ADHD and DD can help in elucidating the molecular mechanisms underlying the comorbid condition, and can also be useful for genotyping and identifying new drug targets.
RESULTS
Using the ANDSystem tool, the reconstruction and analysis of gene networks associated with ADHD and dyslexia was carried out. The gene network of ADHD included 599 genes/proteins and 148,978 interactions, while that of dyslexia included 167 genes/proteins and 27,083 interactions. When the ANDSystem and GeneCards data were combined, a total of 213 genes/proteins for ADHD and dyslexia were found. An approach for ranking genes implicated in the comorbid condition of the two diseases was proposed. The approach is based on ten criteria for ranking genes by their importance, including relevance scores of association between disease and genes, standard methods of gene prioritization, as well as original criteria that take into account the characteristics of an associative gene network and the presence of known polymorphisms in the analyzed genes. Among the top 20 genes with the highest priority DRD2, DRD4, CNTNAP2 and GRIN2B are mentioned in the literature as directly linked with the comorbidity of ADHD and dyslexia. According to the proposed approach, the genes OPRM1, CHRNA4 and SNCA had the highest priority in the development of comorbidity of these two diseases. Additionally, it was revealed that the most relevant genes are involved in biological processes related to signal transduction, positive regulation of transcription from RNA polymerase II promoters, chemical synaptic transmission, response to drugs, ion transmembrane transport, nervous system development, cell adhesion, and neuron migration.
CONCLUSIONS
The application of methods of reconstruction and analysis of gene networks is a powerful tool for studying the molecular mechanisms of comorbid conditions. The method put forth to rank genes by their importance for the comorbid condition of ADHD and dyslexia was employed to predict genes that play key roles in the development of the comorbid condition. The results can be utilized to plan experiments for the identification of novel candidate genes and search for novel pharmacological targets.
Topics: Humans; Child; Attention Deficit Disorder with Hyperactivity; Gene Regulatory Networks; Dyslexia; Comorbidity; Cell Movement
PubMed: 37667328
DOI: 10.1186/s12920-023-01502-1 -
Trends in Cognitive Sciences Jun 2017Developmental dyslexia (decoding-based reading disorder; RD) is a complex trait with multifactorial origins at the genetic, neural, and cognitive levels. There is... (Review)
Review
Developmental dyslexia (decoding-based reading disorder; RD) is a complex trait with multifactorial origins at the genetic, neural, and cognitive levels. There is evidence that low-level sensory-processing deficits precede and underlie phonological problems, which are one of the best-documented aspects of RD. RD is also associated with impairments in integrating visual symbols with their corresponding speech sounds. Although causal relationships between sensory processing, print-speech integration, and fluent reading, and their neural bases are debated, these processes all require precise timing mechanisms across distributed brain networks. Neural excitability and neural noise are fundamental to these timing mechanisms. Here, we propose that neural noise stemming from increased neural excitability in cortical networks implicated in reading is one key distal contributor to RD.
Topics: Auditory Perception; Auditory Perceptual Disorders; Dyslexia; Humans; Noise; Phonetics; Reading; Speech Perception
PubMed: 28400089
DOI: 10.1016/j.tics.2017.03.008 -
Annals of Dyslexia Apr 2020Over the last years, several studies have suggested a possible link between dyslexia and deficits in low-level visual processing (e.g., excessive crowding). At the same... (Comparative Study)
Comparative Study
Over the last years, several studies have suggested a possible link between dyslexia and deficits in low-level visual processing (e.g., excessive crowding). At the same time, specially designed "dyslexia-friendly" fonts appeared on the market. This class of fonts presents two main features: the particular graphic characteristics of the letterform designed to avoid confusion between similarly shaped letters, and wider inter-letter and inter-word spacing to limit crowding. The literature testing the efficacy of "dyslexia-friendly" fonts in improving reading accuracy and increasing reading speed is controversial. We evaluated the impact of letterform (with vs. without dyslexia-friendly graphic features), inter-letter spacing (standard vs. increased), and inter-word spacing (standard vs. increased) on reading accuracy and speed. Two groups of 64 children each, with and without dyslexia, read aloud 8 equivalent texts. The data collected failed to show any effect from the letterform. As regards spacing, the data showed that reading speed is impaired by an increase in inter-letter spacing not combined with an adequate increase in inter-word spacing.
Topics: Child; Comprehension; Dyslexia; Female; Humans; Male; Pattern Recognition, Visual; Photic Stimulation; Reading; Visual Perception
PubMed: 32172467
DOI: 10.1007/s11881-020-00194-x -
New Directions For Child and Adolescent... May 2019Current definitions of specific learning disability (SLD) identify a heterogeneous population that includes individuals with weaknesses in reading, math, or writing, and... (Review)
Review
Current definitions of specific learning disability (SLD) identify a heterogeneous population that includes individuals with weaknesses in reading, math, or writing, and these academic difficulties often co-occur in many of the same individuals. The Colorado Learning Disabilities Research Center (CLDRC) is an interdisciplinary, multisite research program that uses converging levels of analysis to understand the genetic and environmental etiology, neuropsychology, and developmental outcomes of SLDs in reading (RD), math (MD), and writing (WD), along with the comorbidity between these SLDs and other developmental disorders. The latest results from the CLDRC twin study suggest that shared genetic influences contribute to the significant covariance between all aspects of reading (word reading, reading fluency, and reading comprehension) and math (calculations, math fluency, and word problems), and distinct genetic or environmental influences also contribute to weaknesses in each specific academic domain. RD and MD are associated with a range of negative outcomes on both concurrent measures and measures of functional outcomes completed 5 years after the twins were first assessed. Over the next several years the CLDRC will continue to expand on this work by administering a comprehensive test battery that includes measures of all dimensions of academic achievement that are described in current definitions of SLD and incorporating these measures in new neuroimaging and molecular genetic studies.
Topics: Adolescent; Child; Comorbidity; Dyscalculia; Dyslexia; Humans; Twin Studies as Topic
PubMed: 31070302
DOI: 10.1002/cad.20291 -
Deutsches Arzteblatt International Apr 2011
Topics: Child; Dyslexia; Germany; Humans; Neuropsychological Tests; Practice Guidelines as Topic; Psychotherapy; Shame
PubMed: 21556264
DOI: 10.3238/arztebl.2011.0262a -
Language, Speech, and Hearing Services... Oct 2023The purpose of this exploratory study was to evaluate speech-language pathologists' (SLPs') conceptions and misconceptions about dyslexia.
PURPOSE
The purpose of this exploratory study was to evaluate speech-language pathologists' (SLPs') conceptions and misconceptions about dyslexia.
METHOD
Participants were 86 school-based SLPs. They completed an online survey on which they rated their agreement and disagreement with true and false statements related to the scientific evidence about the nature of dyslexia and interventions for dyslexia, as well as common misconceptions about dyslexia.
RESULTS
There was considerable variability among SLPs' agreement and disagreement with the statements. Critically, despite abundant contrary evidence in the literature, many SLPs believe that dyslexia involves a visual processing deficit.
CONCLUSIONS
These findings suggest that many school-based SLPs hold misconceptions about dyslexia, especially those related to dyslexia being a visual disorder. The identified misconceptions may contribute to some SLPs' reluctance to incorporate reading and prereading skills into speech-language assessment and intervention. SLPs need greater knowledge of dyslexia to provide more effective evaluations and intervention services.
Topics: Humans; Speech; Pathologists; Dyslexia; Communication Disorders; Speech Therapy; Surveys and Questionnaires; Speech-Language Pathology
PubMed: 37672782
DOI: 10.1044/2023_LSHSS-22-00199