Reduced size of corpus callosum in autism.

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.