The relationship between motor control and phonology in dyslexic children

Background: The goal of this study was to investigate the automaticity/cerebellar theory of dyslexia. We tested phonological skills and cerebellar function in a group of dyslexic 8-12 year old children and their matched controls. Tests administered included the Phonological Assessment Battery, postural stability, bead threading, finger to thumb and time estimation. Results: Dyslexic children were found to be significantly poorer than the controls at all tasks but time estimation. About 75% of dyslexics were more than one standard deviation below controls in phonological ability, and 50% were similarly impaired in motor skills. However, at least part of the discrepancy in motor skills was due to dyslexic individuals who had additional disorders (ADHD and/or DCD). The absence of evidence for a time estimation deficit also casts doubt on the cerebellar origin of the motor deficiency. About half the dyslexic children didn't have any motor problem, and there was no evidence for a causal relationship between motor skills on the one hand and phonological and reading skills on the other. Conclusion: This study provides partial support for the presence of motor problems in dyslexic children, but does not support the hypothesis that a cerebellar dysfunction is the cause of their phonological and reading impairment

Working memory in children with developmental disorders

The aim of the present study was to directly compare working memory skills across students with different developmental disorders to investigate whether the uniqueness of their diagnosis would impact memory skills. The authors report findings confirming differential memory profiles on the basis of the following developmental disorders: Specific Language Impairment, Developmental Coordination Disorder (DCD), Attention-Deficit/Hyperactivity Disorder, and Asperger syndrome(AS). Specifically, language impairments were associated with selective deficits in verbal short-term and working memory, whereas motor impairments (DCD) were associated with selective deficits in visuospatial short-term and working memory. Children with attention problems were impaired in working memory in both verbal and visuospatial domains, whereas the children with AS had deficits in verbal short-term memory but not in any other memory component. The implications of these findings are discussed in light of support for learning

Handwriting speed in children with Developmental Coordination Disorder: Are they really slower?

This is the post-print version of the final paper published in Research in Developmental Disabilities. The published article is available at the link below. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. Copyright @ 2013 Elsevier B.V.Handwriting difficulties are often included in descriptions of Developmental Coordination Disorder (DCD). They are cited as the most common reason for referral to health professionals following parent and teacher concerns about slow and untidy writing. The aim of this study was to compare handwriting performance in English children with and without DCD across a range of writing tasks, to gain a better understanding of the nature of ‘slowness’ so commonly reported. Twenty-eight 8–14 year-old children with a diagnosis of DCD participated in the study, with 28 typically developing age and gender matched controls. Participants completed the four handwriting tasks from the Detailed Assessment of Speed of Handwriting (DASH) and wrote their own name; all on a digitising writing tablet. The number of words written, speed of pen movements and the time spent pausing during the tasks were calculated. The findings confirmed what many professionals report, that children with DCD produce less text than their peers. However, this was not due to slow movement execution, but rather a higher percentage of time spent pausing. Discussion centres on the understanding of the pausing phenomenon in children with DCD and areas for further research.Oxford Brookes Universit

WISC-IV Profiles in Children with Attention Deficit Hyperactivity Disorder and Comorbid Learning Disabilities

Attention Deficit Hyperactivity Disorder (ADHD) and learning disabilities (LD), including Reading Disorder (RD), Disorder of Written Expression (DWE), and Developmental Coordination Disorder (DCD) all co-occur at high rates. Previous research indicates increased neurocognitive impairment in ADHD with the presence of comorbid diagnoses. However, few direct comparisons between intellectual profiles of children with one or multiple ADHD and LD diagnoses are available, specifically for the Wechsler Intelligence Scale Fourth Edition (WISC-IV), despite its frequent and historical use with this population. Profile analysis may contribute insights into spared and impaired abilities. Therefore, the present study addressed these matters by comparing WISC-IV profiles of children with ADHD and comorbid LD. Participants included 301 children with ADHD-Inattentive (n=101), ADHD-Combined (n=79), ADHD-DCD (n=42), and ADHD-RD and/or Disorder of Written Expression (ADHD-RD-DWE) (n=79). Children were 10.2 years old, 69% male, with a Full Scale IQ of 101.5. Diagnoses of ADHD and learning disorders were established through comprehensive evaluations including behavioral symptom ratings, interviews with parents, and neuropsychological measures. Results indicated a significant group by Index score interaction, which was primarily caused by the ADHD-RD-DWE group performing significantly worse (pPRI\u3eWorking Memory\u3eProcessing Speed). Differences in ADHD presentations were also found, with the ADHD-Inattentive group exhibiting slower processing speed than the ADHD-Combined group. Findings indicate differences in intellectual profiles of children with ADHD and LD as well as ADHD presentations. The combination of LD and ADHD results in unique intellectual profiles, indicating clinical and theoretical utility in distinguishing between these disorders. Further investigation is needed to determine the extent to which these profiles are predictive of academic, social, and behavioral outcomes

Simple and complex motor skills in children with dyslexia and/or attention deficit/hyperactivity disorder : towards a unifying framework of sequential motor impairments in neurodevelopmental disorders

Les difficultés motrices sont de plus en plus rapportées à travers différentes maladies neurologiques incluant les troubles neurodéveloppementaux et les troubles neurodégénératifs. À partir de ces observations, des théories ont émergé et suggèrent que la co-occurrence de symptômes moteurs à travers les maladies neurologiques pourrait être un indicateur de mécanismes neurologiques aberrants communs aux différents troubles, ainsi qu’un indice de vulnérabilité cérébrale. La dyslexie et le trouble déficitaire de l’attention avec ou sans hyperactivité (TDA/H) sont deux troubles neurodéveloppementaux avec une prévalence élevée, qui sont associés à une multitude de difficultés cognitives et motrices, lesquelles se chevauchent fréquemment. L’existence simultanée de symptômes cognitifs est généralement bien reconnue et plusieurs auteurs ont développé des théories qui unifient les troubles neurodéveloppementaux afin d’expliquer cette co-occurrence. Cependant, moins d’accent a été mis sur la présence concomitante de difficultés motrices, possiblement en raison des résultats contradictoires dans la littérature en ce qui a trait à la présence des déficits moteurs. Ces divergences sont à leur tour probablement liées aux multiples outils utilisés pour l’évaluation des troubles moteurs. De plus, peu d’études ont exploré quelles composantes des habiletés motrices sont affectées de manière similaire chez les populations atteintes de dyslexie ou du TDA/H. L’objectif de cette thèse est de clarifier la co-occurrence de difficultés motrices chez des enfants et adolescents atteints d’une dyslexie ou d’un TDA/H en évaluant plusieurs composantes du fonctionnement moteur. De plus, la présence d’une association entre les symptômes cognitifs communs et les difficultés motrices est examinée afin d’appuyer l’hypothèse selon laquelle les mécanismes neurologiques atypiques qui sous-tendent les problèmes moteurs sont similaires dans les deux conditions (dyslexie et TDA/H). Cette thèse est composée de deux études empiriques. Le premier article évalue les habiletés motrices fines et globales avec des tâches qui varient entre la coordination simple et la coordination séquentielle plus complexe, et ce chez des enfants et adolescents qui ont reçu un diagnostic de dyslexie seulement, de TDA/H seulement ou un diagnostic comorbide. Les résultats suggèrent que les enfants avec une dyslexie et/ou un TDA/H présentent des difficultés motrices co-occurrentes en coordination unimanuelle et bimanuelle séquentielle en comparaison à des enfants qui ont un développement typique. Par ailleurs, la vitesse motrice simple est préservée chez ces premiers. De plus, les enfants avec un TDA/H seulement ont des difficultés plus prononcées sur une tâche de coordination bimanuelle asynchronisée et ils obtiennent des résultats déficitaires sur une tâche de dextérité manuelle. Ces résultats suggèrent que les enfants avec un TDA/H ont des difficultés motrices plus sévères et plus étendues. Le deuxième article explore la relation entre les habiletés cognitives et les difficultés en motricité séquentielle chez les enfants avec une dyslexie et/ou un TDA/H. Les résultats indiquent que les habiletés communes en mémoire de travail visuelle et en fluence mathématique sont des prédicteurs des difficultés motrices, sans différentiation entre les groupes. Toutefois, une exception a été observée chez le groupe TDA/H pour lequel les habiletés en fluence mathématique ne contribuent pas significativement aux habiletés bimanuelles synchronisées. De plus, les symptômes diagnostiques de chaque syndrome, soit la lecture en dyslexie et l’inattention dans le TDAH, ne contribuent pas significativement à prédire la performance motrice. Les résultats appuient la notion de la présence de mécanismes neurologiques communs qui sous-tendent ces difficultés motrices analogues. Cette thèse suggère que les enfants avec une dyslexie et/ou un TDA/H présentent fréquemment des difficultés communes en motricité séquentielle. À notre connaissance, ces résultats sont parmi les premiers à suggérer que la dyslexie et le TDA/H présentent une relation similaire entre leurs symptômes cognitifs et moteurs. Ces conclusions appuient l’hypothèse selon laquelle la dyslexie et le TDA/H sont différentes facettes d’une atypie développementale commune et que des difficultés en motricité séquentielle pourraient être un indicateur d’une vulnérabilité cérébrale. Ces résultats fournissent des informations importantes qui permettraient de guider l’évaluation et le dépistage des troubles neurodéveloppementaux. Ils encouragent également le développement et la mise en place d’interventions motrices qui intègrent la planification motrice séquentielle.There is growing evidence that motor abnormalities are present in many neurological illnesses, ranging from neurodevelopmental disorders to neurodegenerative dementia. Theories have emerged suggesting that co-occurring motor impairments across disorders can be indicators of a vulnerable brain state and common aberrant underlying mechanisms. Dyslexia and Attention Deficit disorder with or without hyperactivity (AD) are two prevalent neurodevelopmental disorders and are associated with a collection of cognitive and motor symptoms that often co-occur. The co-occurrence of cognitive symptoms across dyslexia and AD is generally accepted and authors have developed unifying frameworks to better understand accumulating evidence of overlapping symptoms. However, less emphasis has been placed on co-occurring motor impairments, in part due to the inconsistency of findings associated with the many different assessment tools used across studies. In addition, few studies have explored what components of motor abilities are similarly impaired in both disorders. The objective of the current thesis is to clarify the presence of co-occurring motor difficulties in dyslexia and AD by assessing a variety of abilities associated with motor functioning. In addition, the relationship between co-occurring cognitive symptoms and motor difficulties is examined across both disorders to support the putative presence of a common aberrant mechanism that may underlie co-occurring motor weaknesses in dyslexia and AD. The thesis is comprised of two empirical articles. The first paper assesses fine and gross motor abilities that range from simple to complex sequential coordination, in children with dyslexia only, AD only, and both disorders (Combo). Results suggest that children with dyslexia and/or AD have co-occurring difficulties compared to their typically developing peers on unimanual and bimanual sequential coordination in the presence of preserved simple motor speed. In addition, children with AD have more severe problems in complex bimanual out-of-phase coordination and are impaired on measures of dexterity. These results suggest that children with AD may have weaknesses on a wider range of motor abilities and have more profound bimanual coordination difficulties. The second paper examines the relationship between cognitive abilities and co-occurring sequential motor difficulties in dyslexia and AD. Capabilities in visual working memory and math fluency were found to be significant predictors of motor abilities without differentiation between disorders, with one exception by which math fluency did not contribute to performance on bimanual in-phase coordination in the AD group. Moreover, the distinctive symptoms of reading in dyslexia and inattention in AD did not contribute significantly to sequential motor performance. The results suggest that the pattern of motor difficulties is similar in dyslexia and AD, and support the presence of common mechanisms that underlie co-occurring motor weaknesses. We suggest that dyslexia and AD often have co-occurring sequential motor difficulties, and to our knowledge these findings are among the first to show a shared relationship between cognitive abilities and sequential motor weaknesses. The findings support the idea that dyslexia and AD are different facets of a common atypical development and that shared sequential motor difficulties are indicators of a vulnerable brain state. The findings provide important information to help guide assessment and early screening of neurodevelopmental disorders, as well as encourage the development and application of motor intervention programs that integrate sequential motor planning