CEREBELLUM physiology, CEREBRAL hemispheres, CENTRAL nervous system stimulants, NEURAL pathways, ATTENTION-deficit hyperactivity disorder, HUMAN growth, INTELLECT, LONGITUDINAL method, REGRESSION analysis, SEX distribution, STATISTICS, COMORBIDITY, DATA analysis, PHYSIOLOGY, DIAGNOSIS, and THERAPEUTICS
Background: The cerebellum supports many cognitive functions disrupted in attention deficit hyperactivity disorder (ADHD). Prior neuroanatomic studies have been often limited by small sample sizes, inconsistent findings, and a reliance on cross‐sectional data, limiting inferences about cerebellar development. Here, we conduct a multicohort study using longitudinal data, to characterize cerebellar development. Methods: Growth trajectories of the cerebellar vermis, hemispheres and white matter were estimated using piecewise linear regression from 1,656 youth; of whom 63% had longitudinal data, totaling 2,914 scans. Four cohorts participated, all contained childhood data (age 4–12 years); two had adolescent data (12–25 years). Growth parameters were combined using random‐effects meta‐analysis. Results: Diagnostic differences in growth were confined to the corpus medullare (cerebellar white matter). Here, the ADHD group showed slower growth in early childhood compared to the typically developing group (left corpus medullare z = 2.49, p = .01; right z = 2.03, p = .04). This reversed in late childhood, with faster growth in ADHD in the left corpus medullare (z = 2.06, p = .04). Findings held when gender, intelligence, comorbidity, and psychostimulant medication were considered. Discussion: Across four independent cohorts, containing predominately longitudinal data, we found diagnostic differences in the growth of cerebellar white matter. In ADHD, slower white matter growth in early childhood was followed by faster growth in late childhood. The findings are consistent with the concept of ADHD as a disorder of the brain's structural connections, formed partly by developing cortico‐cerebellar white matter tracts. [ABSTRACT FROM AUTHOR]
Belmonte, Matthew K., Gomot, Marie, and Baron‐Cohen, Simon
Journal of Child Psychology & Psychiatry. Mar2010, Vol. 51 Issue 3, p259-276. 18p. 1 Color Photograph, 1 Black and White Photograph, 1 Diagram, 3 Charts, 3 Graphs.
VISUAL perception, SOCIAL perception, AUTISM spectrum disorders, PERCEPTION, ATTENTION, and AUTISM
Background: In addition to their more clinically evident abnormalities of social cognition, people with autism spectrum conditions (ASC) manifest perturbations of attention and sensory perception which may offer insights into the underlying neural abnormalities. Similar autistic traits in ASC relatives without a diagnosis suggest a continuity between clinically affected and unaffected family members. Methods: We applied fMRI in the context of a non-social task of visual attention in order to determine whether this continuity persists at the level of brain physiology. Results: Both boys with ASC and clinically unaffected brothers of people with ASC were impaired at a visual divided-attention task demanding conjunction of attributes from rapidly and simultaneously presented, spatially disjoint stimuli and suppression of spatially intervening distractors. In addition, both groups in comparison to controls manifested atypical fronto-cerebellar activation as a function of distractor congruence, and the degree of this frontal atypicality correlated with psychometric measures of autistic traits in ASC and sibs. Despite these resemblances between the ASC and sib groups, an exploratory, hypothesis-generating analysis of correlations across brain regions revealed a decrease in overall functional correlation only in the ASC group and not in the sibs. Conclusions: These results establish a neurophysiological correlate of familial susceptibility to ASC, and suggest that whilst abnormal time courses of frontal activation may reflect processes permissive of autistic brain development, abnormal patterns of functional correlation across a wider array of brain regions may relate more closely to autism’s determinants. [ABSTRACT FROM AUTHOR]
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 77% of dyslexics were more than one standard deviation below controls in phonological ability, and 59% 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. [ABSTRACT FROM AUTHOR]