Dyslexia and corpus callosum morphology.

OBJECTIVE There is evolving evidence that developmental dyslexia is associated with anomalous cerebral morphology in the bilateral frontal and left temporoparietal regions. This study examined the morphology of the corpus callosum, as possible deviations in other important structures are poorly understood in this behaviorally diagnosed syndrome. DESIGN Magnetic resonance imaging scans were obtained from children with developmental dyslexia and from matched control children. Morphometric measurements were examined to determine if regional differences existed in the corpus callosum between these two groups of children. SETTING Magnetic resonance imaging studies were completed at Athens (Ga) Magnetic Imaging. PATIENTS AND OTHER PARTICIPANTS Sixteen developmental dyslexic children (mean age, 9.7 years) and a matched sample of children who were diagnosed as being normal were examined by using a reliable comprehensive diagnostic process. MAIN OUTCOME MEASURES Using a midsagittal magnetic resonance imaging scan, corpus callosum morphology was evaluated by segmenting the corpus callosum into five regions of interest. RESULTS Analysis of the corpus callosum revealed that the anterior region of interest (the genu) was significantly smaller in the dyslexic children. Significant correlations existed between reading achievement and the region-of-interest measurements for the genu and splenium. Measured intelligence, chronologic age, and gender were not related to region-of-interest measurements of the corpus callosum. Consistent with previous studies, the dyslexic individuals were characterized by significant psychiatric comorbidity, particularly attention-deficit disorder with and without hyperactivity. Reported familial left-handedness also distinguished the dyslexic children. CONCLUSIONS Subtle neurodevelopmental variation in the morphology of the corpus callosum may be associated with the difficulty that dyslexic children experience in reading and on tasks involving interhemispheric transfer.

[1]  C. Leonard,et al.  Anomalous cerebral structure in dyslexia revealed with magnetic resonance imaging. , 1993, Archives of neurology.

[2]  G. Hynd,et al.  Attention-Deficit Disorder With (ADD/H) and Without (ADD/WO) Hyperactivity: Behavioral and Neuropsychological Differentiation , 1992 .

[3]  J. Rumsey,et al.  Failure to activate the left temporoparietal cortex in dyslexia. An oxygen 15 positron emission tomographic study. , 1992, Archives of neurology.

[4]  Torleiv Høien,et al.  Magnetic resonance imaging of the corpus callosum in developmental dyslexia , 1992 .

[5]  U Bellugi,et al.  Callosal morphology concurs with neurobehavioral and neuropathological findings in two neurodevelopmental disorders. , 1992, Archives of neurology.

[6]  M. Bryden,et al.  Geschwind's theory of cerebral lateralization: developing a formal, causal model. , 1991, Psychological bulletin.

[7]  D. Loewenstein,et al.  Positron emission tomographic studies during serial word-reading by normal and dyslexic adults. , 1991, Journal of clinical and experimental neuropsychology.

[8]  H. Lubs,et al.  Neuroanatomic differences between dyslexic and normal readers on magnetic resonance imaging scans. , 1991, Archives of neurology.

[9]  G. Hynd,et al.  Attention Deficit Disorder Without Hyperactivity: A Distinct Behavioral and Neurocognitive Syndrome , 1991 .

[10]  J. Fletcher,et al.  Prevalence of reading disability in boys and girls. Results of the Connecticut Longitudinal Study. , 1990, JAMA.

[11]  G. Hynd,et al.  Brain morphology in developmental dyslexia and attention deficit disorder/hyperactivity. , 1990, Archives of neurology.

[12]  B. Pennington,et al.  Familial dyslexia: use of genetic linkage data to define subtypes. , 1990, Journal of the American Academy of Child and Adolescent Psychiatry.

[13]  G. Hynd,et al.  Dyslexia and brain morphology. , 1989, Psychological bulletin.

[14]  C. Best,et al.  Cognitive processing deficits in reading disabilities: A prefrontal cortical hypothesis , 1989, Brain and Cognition.

[15]  S. F. Witelson.  Hand and sex differences in the isthmus and genu of the human corpus callosum. A postmortem morphological study. , 1989, Brain : a journal of neurology.

[16]  D. Duane.  Neurobiological correlates of learning disorders. , 1989, Journal of the American Academy of Child and Adolescent Psychiatry.

[17]  E. Zaidel.  Hemispheric Independence and Interaction in Word Recognition , 1989 .

[18]  J. O’Kusky,et al.  The corpus callosum is larger with right‐hemisphere cerebral speech dominance , 1988, Annals of neurology.

[19]  M. Haith,et al.  Left-handedness and immune disorders in familial dyslexics. , 1987, Archives of neurology.

[20]  B. Lahey,et al.  Teacher ratings of attention problems in children experimentally classified as exhibiting attention deficit disorder with and without hyperactivity. , 1985, Journal of the American Academy of Child Psychiatry.

[21]  S. F. Witelson.  The brain connection: the corpus callosum is larger in left-handers. , 1985, Science.

[22]  N. Geschwind,et al.  Developmental dyslexia: Four consecutive patients with cortical anomalies , 1985, Annals of neurology.

[23]  Language in the nondominant right hemisphere. , 1983, Archives of neurology.

[24]  T. L. Harris,et al.  A Dictionary of Reading and Related Terms. , 1983 .

[25]  G. Hynd,et al.  Dyslexia: Neuropsychological Theory, Research, and Clinical Differentiation , 1983 .

[26]  T. Shallice.  Specific impairments of planning. , 1982, Philosophical transactions of the Royal Society of London. Series B, Biological sciences.

[27]  B. Milner.  Some cognitive effects of frontal-lobe lesions in man. , 1982, Philosophical transactions of the Royal Society of London. Series B, Biological sciences.

[28]  R. Holloway,,et al.  Sexual dimorphism in the human corpus callosum. , 1982, Science.

[29]  G. Innocenti.  The development of interhemispheric connections , 1981, Trends in Neurosciences.

[30]  R. Goldman,et al.  Left-Handedness and Cognitive Deficit , 1976, Cortex.

[31]  M. Gazzaniga.  BRAIN THEORY AND MINIMAL BRAIN DYSFUNCTION * , 1973, Annals of the New York Academy of Sciences.

[32]  R. C. Oldfield.  The assessment and analysis of handedness: the Edinburgh inventory. , 1971, Neuropsychologia.

[33]  J. Fleiss,et al.  Quantification of agreement in psychiatric diagnosis. A new approach. , 1967, Archives of general psychiatry.

[34]  J. Hinshelwood.  Congenital word-blindness , 1917 .