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Fletcher JM, Miciak J. Assessment of Specific Learning Disabilities and Intellectual Disabilities. Assessment 2024; 31:53-74. [PMID: 37671726 PMCID: PMC10795803 DOI: 10.1177/10731911231194992] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/07/2023]
Abstract
We review literature related to the assessment and identification of Specific Learning Disabilities (SLD) and Intellectual Disabilities (ID). SLD and ID are the only two disorders requiring psychometric test performance for identification within the group of neurodevelopmental disorders in Diagnostic and Statistical Manual - 5. SLD and ID are considered exclusionary of one another, but the processes for assessment and identification of each disorder vary. There is controversy about the identification and assessment methods for SLD, with little consensus. Unlike ID, SLD is weakly related to full-scale IQ, and there is insufficient evidence that the routine assessment of IQ or cognitive skills adds value to SLD identification and treatment. We have proposed a hybrid method based on the assessment of low achievement with norm-referenced tests, instructional response, and other disorders and contextual factors that may be comorbid or contraindicative of SLD. In contrast to SLD, there is strong consensus for a three-prong definition for the identification and assessment of ID: (a) significantly subaverage IQ, (b) adaptive behavior deficits that interfere with independent living in the community, and (c) age of onset in the developmental period. For both SLD and ID, we identify areas of controversy and best practices for identification and assessment.
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Unger N, Heim S, Hilger DI, Bludau S, Pieperhoff P, Cichon S, Amunts K, Mühleisen TW. Identification of Phonology-Related Genes and Functional Characterization of Broca's and Wernicke's Regions in Language and Learning Disorders. Front Neurosci 2021; 15:680762. [PMID: 34539327 PMCID: PMC8446646 DOI: 10.3389/fnins.2021.680762] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Accepted: 08/04/2021] [Indexed: 12/02/2022] Open
Abstract
Impaired phonological processing is a leading symptom of multifactorial language and learning disorders suggesting a common biological basis. Here we evaluated studies of dyslexia, dyscalculia, specific language impairment (SLI), and the logopenic variant of primary progressive aphasia (lvPPA) seeking for shared risk genes in Broca's and Wernicke's regions, being key for phonological processing within the complex language network. The identified "phonology-related genes" from literature were functionally characterized using Atlas-based expression mapping (JuGEx) and gene set enrichment. Out of 643 publications from the last decade until now, we extracted 21 candidate genes of which 13 overlapped with dyslexia and SLI, six with dyslexia and dyscalculia, and two with dyslexia, dyscalculia, and SLI. No overlap was observed between the childhood disorders and the late-onset lvPPA often showing symptoms of learning disorders earlier in life. Multiple genes were enriched in Gene Ontology terms of the topics learning (CNTNAP2, CYFIP1, DCDC2, DNAAF4, FOXP2) and neuronal development (CCDC136, CNTNAP2, CYFIP1, DCDC2, KIAA0319, RBFOX2, ROBO1). Twelve genes showed above-average expression across both regions indicating moderate-to-high gene activity in the investigated cortical part of the language network. Of these, three genes were differentially expressed suggesting potential regional specializations: ATP2C2 was upregulated in Broca's region, while DNAAF4 and FOXP2 were upregulated in Wernicke's region. ATP2C2 encodes a magnesium-dependent calcium transporter which fits with reports about disturbed calcium and magnesium levels for dyslexia and other communication disorders. DNAAF4 (formerly known as DYX1C1) is involved in neuronal migration supporting the hypothesis of disturbed migration in dyslexia. FOXP2 is a transcription factor that regulates a number of genes involved in development of speech and language. Overall, our interdisciplinary and multi-tiered approach provided evidence that genetic and transcriptional variation of ATP2C2, DNAAF4, and FOXP2 may play a role in physiological and pathological aspects of phonological processing.
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Affiliation(s)
- Nina Unger
- Cécile and Oskar Vogt Institute for Brain Research, Medical Faculty, University Hospital Düsseldorf, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
- Institute of Neuroscience and Medicine (INM-1), Research Centre Jülich, Jülich, Germany
- Department of Neurology, Medical Faculty, RWTH Aachen University, Aachen, Germany
| | - Stefan Heim
- Institute of Neuroscience and Medicine (INM-1), Research Centre Jülich, Jülich, Germany
- Department of Psychiatry, Psychotherapy and Psychosomatics, Medical Faculty, RWTH Aachen University, Aachen, Germany
- JARA-Brain, Jülich-Aachen Research Alliance, Jülich, Germany
| | - Dominique I. Hilger
- Institute of Neuroscience and Medicine (INM-1), Research Centre Jülich, Jülich, Germany
| | - Sebastian Bludau
- Institute of Neuroscience and Medicine (INM-1), Research Centre Jülich, Jülich, Germany
| | - Peter Pieperhoff
- Institute of Neuroscience and Medicine (INM-1), Research Centre Jülich, Jülich, Germany
| | - Sven Cichon
- Institute of Neuroscience and Medicine (INM-1), Research Centre Jülich, Jülich, Germany
- Department of Biomedicine, University of Basel, Basel, Switzerland
- Institute of Medical Genetics and Pathology, University Hospital Basel, Basel, Switzerland
| | - Katrin Amunts
- Cécile and Oskar Vogt Institute for Brain Research, Medical Faculty, University Hospital Düsseldorf, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
- Institute of Neuroscience and Medicine (INM-1), Research Centre Jülich, Jülich, Germany
- JARA-Brain, Jülich-Aachen Research Alliance, Jülich, Germany
| | - Thomas W. Mühleisen
- Cécile and Oskar Vogt Institute for Brain Research, Medical Faculty, University Hospital Düsseldorf, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
- Institute of Neuroscience and Medicine (INM-1), Research Centre Jülich, Jülich, Germany
- Department of Biomedicine, University of Basel, Basel, Switzerland
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Martins M, Reis AM, Castro SL, Gaser C. Gray matter correlates of reading fluency deficits: SES matters, IQ does not. Brain Struct Funct 2021; 226:2585-2601. [PMID: 34357437 DOI: 10.1007/s00429-021-02353-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Accepted: 07/26/2021] [Indexed: 02/05/2023]
Abstract
Brain correlates of reading ability have been intensely investigated. Most studies have focused on single-word reading and phonological processing, but the brain basis of reading fluency remains poorly explored to date. Here, in a voxel-based morphometry study with 8-year-old children, we compared fluent readers (n = 18; seven boys) with dysfluent readers with normal IQ (n = 18; six boys) and with low IQ (n = 18; ten boys). Relative to dysfluent readers, fluent readers had larger gray matter volume in the right superior temporal gyrus and the two subgroups of dysfluent readers did not differ from each other, as shown in frequentist and Bayesian analyses. Pairwise comparisons showed that dysfluent readers of normal and low IQ did not differ in core reading regions and that both subgroups had less gray matter volume than fluent readers in occipito-temporal, parieto-temporal and fusiform areas. We also examined gray matter volume in matched subgroups of dysfluent readers differing only in socioeconomic status (SES): lower-SES (n = 14; seven boys) vs. higher-SES (n = 14; seven boys). Higher-SES dysfluent readers had larger gray matter volume in the right angular gyrus than their lower-SES peers, and the volume of this cluster correlated positively with lexico-semantic fluency. Age, sex, IQ, and gray matter volume of the right angular cluster explained 68% of the variance in the reading fluency of higher-SES dysfluent readers. In sum, this study shows that gray matter correlates of dysfluent reading are independent of IQ, and suggests that SES modulates areas sub-serving lexico-semantic processes in dysfluent readers-two findings that may be useful to inform language/reading remediation programs.
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Affiliation(s)
- Marta Martins
- Instituto Universitário de Lisboa (ISCTE-IUL), Lisboa, Portugal
- Center for Psychology, Faculty of Psychology and Education Sciences, University of Porto, Rua Alfredo Allen, 4200-135, Porto, Portugal
| | | | - São Luís Castro
- Center for Psychology, Faculty of Psychology and Education Sciences, University of Porto, Rua Alfredo Allen, 4200-135, Porto, Portugal.
| | - Christian Gaser
- Department of Psychiatry, Jena University Hospital, Jena, Germany
- Department of Neurology, Jena University Hospital, Jena, Germany
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Abstract
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).
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Psychometric Markers of Genuine and Feigned Neurodevelopmental Disorders in the Context of Applying for Academic Accommodations. PSYCHOLOGICAL INJURY & LAW 2017. [DOI: 10.1007/s12207-017-9287-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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A review of the neurobiological basis of dyslexia in the adult population. NEUROLOGÍA (ENGLISH EDITION) 2017. [DOI: 10.1016/j.nrleng.2014.08.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
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Willems G, Jansma B, Blomert L, Vaessen A. Cognitive and familial risk evidence converged: A data-driven identification of distinct and homogeneous subtypes within the heterogeneous sample of reading disabled children. RESEARCH IN DEVELOPMENTAL DISABILITIES 2016; 53-54:213-231. [PMID: 26922163 DOI: 10.1016/j.ridd.2015.12.018] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Revised: 11/01/2015] [Accepted: 12/05/2015] [Indexed: 06/05/2023]
Abstract
The evident degree of heterogeneity observed in reading disabled children has puzzled reading researchers for decades. Recent advances in the genetic underpinnings of reading disability have indicated that the heritable, familial risk for dyslexia is a major risk factor. The present data-driven, classification attempt aims to revisit the possibility of identifying distinct cognitive deficit profiles in a large sample of second to fourth grade reading disabled children. In this sample, we investigated whether genetic and environmental risk factors are able to distinguish between poor reader subtypes. In this profile, we included reading-related measures of phonemic awareness, letter-speech sound processing and rapid naming, known as candidate vulnerability markers associated with dyslexia and familial risk for dyslexia, as well as general cognitive abilities (non-verbal IQ and vocabulary). Clustering was based on a 200 multi-start K-means approach. Results revealed four emerging subtypes of which the first subtype showed no cognitive deficits underlying their poor reading skills (Reading-only impaired poor readers). The other three subtypes shared a core phonological deficit (PA) with a variable and discriminative expression across the other underlying vulnerability markers. More specific, type 2 showed low to poor performance across all reading-related and general cognitive abilities (general poor readers), type 3 showed a specific letter-speech sound mapping deficit next to a PA deficit (PA-LS specific poor readers) and type 4 showed a specific rapid naming deficit complementing their phonological weakness (PA-RAN specific poor readers). The first three poor reader profiles were more characterized by variable environmental risk factor, while the fourth, PA-RAN poor reader subtype showed a significantly strong familial risk for dyslexia. Overall, when we zoom in on the heterogeneous phenomenon of reading disability, unique and distinct cognitive subtypes can be identified, distinguishing between those poor readers more influences by the role of genes and those more influenced by environmental risk factors. Taking into account this diversity of distinct cognitive subtypes, instead of looking at the reading disabled sample as a whole, will help tailor future diagnostic and intervention efforts more specifically to the needs of children with such a specific deficit and risk pattern, as well as providing a more promising way forward for genetic studies of dyslexia.
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Affiliation(s)
- Gonny Willems
- Department of Cognitive Neuroscience, Faculty of Psychology & Neuroscience, Maastricht University, and Maastricht Brain Imaging Centre (M-BIC), P.O. Box 616, 6200 MD Maastricht, The Netherlands.
| | - Bernadette Jansma
- Department of Cognitive Neuroscience, Faculty of Psychology & Neuroscience, Maastricht University, and Maastricht Brain Imaging Centre (M-BIC), P.O. Box 616, 6200 MD Maastricht, The Netherlands.
| | - Leo Blomert
- Department of Cognitive Neuroscience, Faculty of Psychology & Neuroscience, Maastricht University, and Maastricht Brain Imaging Centre (M-BIC), P.O. Box 616, 6200 MD Maastricht, The Netherlands
| | - Anniek Vaessen
- Department of Cognitive Neuroscience, Faculty of Psychology & Neuroscience, Maastricht University, and Maastricht Brain Imaging Centre (M-BIC), P.O. Box 616, 6200 MD Maastricht, The Netherlands.
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Ozernov-Palchik O, Gaab N. Tackling the 'dyslexia paradox': reading brain and behavior for early markers of developmental dyslexia. WILEY INTERDISCIPLINARY REVIEWS. COGNITIVE SCIENCE 2016; 7:156-76. [PMID: 26836227 DOI: 10.1002/wcs.1383] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Revised: 10/15/2015] [Accepted: 12/23/2015] [Indexed: 01/18/2023]
Abstract
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.
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Affiliation(s)
- Ola Ozernov-Palchik
- Laboratories of Cognitive Neuroscience, Division of Developmental Medicine, Department of Medicine, Boston Children's Hospital, Boston, MA, USA.,Eliot-Pearson Department of Child Study and Human Development, Tufts University, Medford, MA, USA
| | - Nadine Gaab
- Laboratories of Cognitive Neuroscience, Division of Developmental Medicine, Department of Medicine, Boston Children's Hospital, Boston, MA, USA.,Harvard Graduate School of Education, Cambridge, MA, USA
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de Zeeuw EL, de Geus EJ, Boomsma DI. Meta-analysis of twin studies highlights the importance of genetic variation in primary school educational achievement. Trends Neurosci Educ 2015. [DOI: 10.1016/j.tine.2015.06.001] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Affiliation(s)
- Robin L. Peterson
- Department of Rehabilitation Medicine, Children's Hospital Colorado, Aurora, Colorado 80045;
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Soriano-Ferrer M, Piedra Martínez E. A review of the neurobiological basis of dyslexia in the adult population. Neurologia 2014; 32:50-57. [PMID: 25444408 DOI: 10.1016/j.nrl.2014.08.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Accepted: 08/08/2014] [Indexed: 01/18/2023] Open
Abstract
INTRODUCTION Adult dyslexia affects about 4% of the population. However, studies on the neurobiological basis of dyslexia in adulthood are scarce compared to paediatric studies. AIM This review investigates the neurobiological basis of dyslexia in adulthood. DEVELOPMENT Using PsycINFO, a database of psychology abstracts, we identified 11 studies on genetics, 9 neurostructural studies, 13 neurofunctional studies and 24 neurophysiological studies. Results from the review show that dyslexia is highly heritable and displays polygenic transmission. Likewise, adult neuroimaging studies found structural, functional, and physiological changes in the parieto-occipital and occipito-temporal regions, and in the inferior frontal gyrus, in adults with dyslexia. CONCLUSION According to different studies, aetiology in cases of adult dyslexia is complex. We stress the need for neurobiological studies of dyslexia in languages with transparent spelling systems.
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Affiliation(s)
- M Soriano-Ferrer
- Departamento de Psicología Evolutiva y de la Educación, Facultad de Psicología, Universidad de Valencia, Valencia, España.
| | - E Piedra Martínez
- Escuela de Educación Especial, Escuela de Psicología Educativa, Facultad de Filosofía, Universidad del Azuay, Cuenca, Ecuador
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Simos PG, Rezaie R, Papanicolaou AC, Fletcher JM. Does IQ affect the functional brain network involved in pseudoword reading in students with reading disability? A magnetoencephalography study. Front Hum Neurosci 2014; 7:932. [PMID: 24409136 PMCID: PMC3884211 DOI: 10.3389/fnhum.2013.00932] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2013] [Accepted: 12/23/2013] [Indexed: 11/16/2022] Open
Abstract
The study examined whether individual differences in performance and verbal IQ affect the profiles of reading-related regional brain activation in 127 students experiencing reading difficulties and typical readers. Using magnetoencephalography in a pseudoword read-aloud task, we compared brain activation profiles of students experiencing word-level reading difficulties who did (n = 29) or did not (n = 36) meet the IQ-reading achievement discrepancy criterion. Typical readers assigned to a lower-IQ (n = 18) or a higher IQ (n = 44) subgroup served as controls. Minimum norm estimates of regional cortical activity revealed that the degree of hypoactivation in the left superior temporal and supramarginal gyri in both RD subgroups was not affected by IQ. Moreover, IQ did not moderate the positive association between degree of activation in the left fusiform gyrus and phonological decoding ability. We did find, however, that the hypoactivation of the left pars opercularis in RD was restricted to lower-IQ participants. In accordance with previous morphometric and fMRI studies, degree of activity in inferior frontal, and inferior parietal regions correlated with IQ across reading ability subgroups. Results are consistent with current views questioning the relevance of IQ-discrepancy criteria in the diagnosis of dyslexia.
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Affiliation(s)
- Panagiotis G Simos
- Department of Psychiatry, School of Medicine, University of Crete Herakleion, Crete, Greece
| | - Roozbeh Rezaie
- Department of Pediatrics, Division of Clinical Neurosciences, College of Medicine, University of Tennessee Health Science Center Memphis, TN, USA ; Neuroscience Institute-Le Bonheur Children's Hospital Memphis, TN, USA
| | - Andrew C Papanicolaou
- Department of Pediatrics, Division of Clinical Neurosciences, College of Medicine, University of Tennessee Health Science Center Memphis, TN, USA ; Neuroscience Institute-Le Bonheur Children's Hospital Memphis, TN, USA
| | - Jack M Fletcher
- Department of Psychology, University of Houston Houston, TX, USA
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Field LL, Shumansky K, Ryan J, Truong D, Swiergala E, Kaplan BJ. Dense-map genome scan for dyslexia supports loci at 4q13, 16p12, 17q22; suggests novel locus at 7q36. GENES BRAIN AND BEHAVIOR 2012. [PMID: 23190410 DOI: 10.1111/gbb.12003] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Analysis of genetic linkage to dyslexia was performed using 133,165 array-based SNPs genotyped in 718 persons from 101 dyslexia-affected families. Results showed five linkage peaks with lod scores >2.3 (4q13.1, 7q36.1-q36.2, 7q36.3, 16p12.1, and 17q22). Of these five regions, three have been previously implicated in dyslexia (4q13.1, 16p12.1, and 17q22), three have been implicated in attention-deficit hyperactivity disorder (ADHD, which highly co-occurs with dyslexia; 4q13.1, 7q36.3, 16p12.1) and four have been implicated in autism (a condition characterized by language deficits; 7q36.1-q36.2, 7q36.3, 16p12.1, and 17q22). These results highlight the reproducibility of dyslexia linkage signals, even without formally significant lod scores, and suggest dyslexia predisposing genes with relatively major effects and locus heterogeneity. The largest lod score (2.80) occurred at 17q22 within the MSI2 gene, involved in neuronal stem cell lineage proliferation. Interestingly, the 4q13.1 linkage peak (lod 2.34) occurred immediately upstream of the LPHN3 gene, recently reported both linked and associated with ADHD. Separate analyses of larger pedigrees revealed lods >2.3 at 1-3 regions per family; one family showed strong linkage (lod 2.9) to a known dyslexia locus (18p11) not detected in our overall data, demonstrating the value of analyzing single large pedigrees. Association analysis identified no SNPs with genome-wide significance, although a borderline significant SNP (P = 6 × 10(-7)) occurred at 5q35.1 near FGF18, involved in laminar positioning of cortical neurons during development. We conclude that dyslexia genes with relatively major effects exist, are detectable by linkage analysis despite genetic heterogeneity, and show substantial overlapping predisposition with ADHD and autism.
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Affiliation(s)
- L L Field
- Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada
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Cheung CH, Wood AC, Paloyelis Y, Arias-Vasquez A, Buitelaar JK, Franke B, Miranda A, Mulas F, Rommelse N, Sergeant JA, Sonuga-Barke EJ, Faraone SV, Asherson P, Kuntsi J. Aetiology for the covariation between combined type ADHD and reading difficulties in a family study: the role of IQ. J Child Psychol Psychiatry 2012; 53:864-73. [PMID: 22324316 PMCID: PMC3414694 DOI: 10.1111/j.1469-7610.2012.02527.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
BACKGROUND Twin studies using both clinical and population-based samples suggest that the frequent co-occurrence of attention deficit hyperactivity disorder (ADHD) and reading ability/disability (RD) is largely driven by shared genetic influences. While both disorders are associated with lower IQ, recent twin data suggest that the shared genetic variability between reading difficulties and ADHD inattention symptoms is largely independent from genetic influences contributing to general cognitive ability. The current study aimed to extend the previous findings that were based on rating scale measures in a population sample by examining the generalisability of the findings to a clinical population, and by measuring reading difficulties both with a rating scale and with an objective task. This study investigated the familial relationships between ADHD, reading difficulties and IQ in a sample of individuals diagnosed with ADHD combined type, their siblings and control sibling pairs. METHODS Multivariate familial models were run on data from 1,789 individuals at ages 6-19. Reading difficulties were measured with both rating scale and an objective task. IQ was obtained using the Wechsler Intelligence Scales (WISC-III/WAIS-III). RESULTS Significant phenotypic (.2-.4) and familial (.3-.5) correlations were observed among ADHD, reading difficulties and IQ. Yet, 53%-72% of the overlapping familial influences between ADHD and reading difficulties were not shared with IQ. CONCLUSIONS Our finding that familial influences shared with general cognitive ability, although present, do not account for the majority of the overlapping familial influences on ADHD and reading difficulties extends previous findings from a population-based study to a clinically ascertained sample with combined type ADHD.
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Affiliation(s)
- Celeste H.M. Cheung
- King’s College London, MRC Social, Genetic and Developmental Psychiatry Centre, Institute of Psychiatry, UK
| | - Alexis C. Wood
- Department of Epidemiology and Section of Statistical Genetics, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Yannis Paloyelis
- King’s College London, Department of Neuroimaging and Department of Psychology, Institute of Psychiatry, UK
| | - Alejandro Arias-Vasquez
- Department of Human Genetics, Radboud University Nijmegen Medical Center, Nijmegen, The Netherlands,Department of Psychiatry, Donders Institute for Brain, Cognition and Behavior, Centre for Neuroscience, Radboud University Nijmegen Medical Center, Nijmegen, The Netherlands
| | - Jan K. Buitelaar
- Department of Cognitive Neuroscience, Donders Institute for Brain, Cognition and Behavior, Centre for Neuroscience, Radboud University Nijmegen Medical Center, Nijmegen, The Netherlands
| | - Barbara Franke
- Department of Human Genetics, Radboud University Nijmegen Medical Center, Nijmegen, The Netherlands,Department of Psychiatry, Donders Institute for Brain, Cognition and Behavior, Centre for Neuroscience, Radboud University Nijmegen Medical Center, Nijmegen, The Netherlands
| | - Ana Miranda
- Department of Developmental and Educational Psychology, University of Valencia, Spain
| | - Fernando Mulas
- Department of Neuropaediatrics, La Fe University Hospital, Faculty of Medicine, Valencia, Spain
| | - Nanda Rommelse
- Department of Psychiatry, Donders Institute for Brain, Cognition and Behavior, Centre for Neuroscience, Radboud University Nijmegen Medical Center, Nijmegen, The Netherlands
| | - Joseph A. Sergeant
- Department of Clinical Neuropsychology, Vrije Universiteit, Amsterdam, The Netherlands
| | - Edmund J. Sonuga-Barke
- Developmental Brain-Behaviour Laboratory, University of Southampton, UK,Department of Experimental Clinical and Health Psychology, Ghent University, Belgium
| | - Stephen V. Faraone
- Department of Neuroscience, SUNY Upstate Medical University, Syracuse, NY, USA,Department of Psychiatry, SUNY Upstate Medical University, Syracuse, NY, USA
| | - Philip Asherson
- King’s College London, MRC Social, Genetic and Developmental Psychiatry Centre, Institute of Psychiatry, UK
| | - Jonna Kuntsi
- King’s College London, MRC Social, Genetic and Developmental Psychiatry Centre, Institute of Psychiatry, UK
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Wadsworth SJ, Olson RK, Willcutt EG, DeFries JC. Multiple regression analysis of reading performance data from twin pairs with reading difficulties and nontwin siblings: the augmented model. Twin Res Hum Genet 2012; 15:116-9. [PMID: 22784461 DOI: 10.1375/twin.15.1.116] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The augmented multiple regression model for the analysis of data from selected twin pairs was extended to facilitate analyses of data from twin pairs and nontwin siblings. Fitting this extended model to data from both selected twin pairs and siblings yields direct estimates of heritability (h2) and the difference between environmental influences shared by members of twin pairs and those of sib or twin-sib pairs (i.e., c2(t) - c2 (s)). When this model was fitted to reading performance data from 293 monozygotic and 436 dizygotic pairs selected for reading difficulties, and 291 of their nontwin siblings, h2 = .48 ± .22, p = .03, and c2 (t) - c2 (s) = .22 ± .12, p = .06. Although the test for differential shared environmental influences is only marginally significant, the results of this analysis suggest that environmental influences on reading performance that are shared by members of twin pairs (.36) may be substantially greater than those for less contemporaneous twin-sibling pairs (.14).
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Affiliation(s)
- Sally J Wadsworth
- Institute for Behavioral Genetics, University of Colorado, Boulder, CO 80309, USA.
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Abstract
Dyslexia is a neurodevelopmental disorder that is characterised by slow and inaccurate word recognition. Dyslexia has been reported in every culture studied, and mounting evidence draws attention to cross-linguistic similarity in its neurobiological and neurocognitive bases. Much progress has been made across research specialties spanning the behavioural, neuropsychological, neurobiological, and causal levels of analysis in the past 5 years. From a neuropsychological perspective, the phonological theory remains the most compelling, although phonological problems also interact with other cognitive risk factors. Work confirms that, neurobiologically, dyslexia is characterised by dysfunction of the normal left hemisphere language network and also implicates abnormal white matter development. Studies accounting for reading experience demonstrate that many recorded neural differences show causes rather than effects of dyslexia. Six predisposing candidate genes have been identified, and evidence shows gene by environment interaction.
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Affiliation(s)
- Robin L Peterson
- Department of Psychology, University of Denver, Denver, CO 80208, USA.
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17
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Genetic and environmental etiologies of reading difficulties: DeFries-Fulker analysis of reading performance data from twin pairs and their nontwin siblings. LEARNING AND INDIVIDUAL DIFFERENCES 2012; 22:365-369. [PMID: 22927712 DOI: 10.1016/j.lindif.2012.01.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Reading performance data from 254 pairs of identical (MZ) and 420 pairs of fraternal (DZ) twins, 8.0 to 20.0 years of age, were subjected to multiple regression analyses. An extension of the DeFries-Fulker (DF) analysis (DeFries & Fulker, 1985, 1988) that facilitated inclusion of data from 303 of their nontwin siblings was employed. In addition to providing estimates of heritability, this analysis yields a test of the difference between shared environmental influences for twins versus siblings (Astrom et al., 2011). Results suggest that proband reading deficits are due substantially to genetic factors (.67 ± .07, p < .001), and that shared environmental influences are significantly higher for members of twin pairs than for those of twins and their nontwin siblings (viz., .25 versus .17, p = .02).
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18
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Abstract
As a relatively young science, neuroscience is still finding its feet in potential collaborations with other disciplines. One such discipline is education, with the field of neuroeducation being on the horizon since the 1960s. However, although its achievements are now growing, the partnership has not been as successful as first hopes suggested it should be. Here the authors discuss the theoretical barriers and potential solutions to this, which have been suggested previously, with particular focus on levels of research in neuroscience and their applicability to education. Moreover, they propose that these theoretical barriers are driven and maintained by practical barriers surrounding common language and research literacy. They propose that by overcoming these practical barriers through appropriate training and shared experience, neuroeducation can reach its full potential.
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Affiliation(s)
- Ian M Devonshire
- Department of Pharmacology, Oxford University, Oxford, United Kingdom
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