Reduced size of corpus callosum in autism

B. Egaas, E. Courchesne and O. Saitoh
Neuropsychology Research Laboratory, Children's Hospital Research Center, San Diego, Calif., USA.

OBJECTIVE: To determine via magnetic resonance imaging if the posterior corpus callosum is reduced in the midline cross-sectional area in autistic patients, consistent with previous reports of parietal lobe abnormalities. DESIGN: Case-control study. SETTING: Tertiary care facility. PATIENTS AND OTHER PARTICIPANTS: Fifty-one autistic patients (45 males and six females; age range, 3 to 42 years), including both mentally retarded and nonretarded patients who met several diagnostic criteria for autism were prospectively selected. Fifty-one age-and sex-matched volunteer normal control subjects were also included. INTERVENTION: None. MAIN OUTCOME MEASURES: Computer-aided measurement of cross-sectional area, areas of five subregions, and thickness profile. RESULTS: Overall size reduction, concentrated in posterior subregions. CONCLUSIONS: Evidence is found of a reduced size of the corpus callosum in autistic patients. This reduction is localized to posterior regions, where parietal lobe fibers are known to project. This finding further supports the idea that parietal lobe involvement may be a consistent feature in autism.