MRI study of corpus callosum abnormalities in bipolar patients

BACKGROUND: This study was conducted to further examine the hypothesis of abnormalities in size of corpus callosum in subjects with bipolar disorder. METHODS: Sixteen right-handed DSM-IV bipolar I patients and 27 right-handed healthy control subjects were studied. A 1.5-T GE Signa magnet was used, and three-dimensional gradient echo imaging (spoiled gradient recall acquisition) was conducted. Area measurements of corpus callosum were obtained blindly, with a semi-automated software, by a well-trained rater. RESULTS: Right-handed bipolar I patients had significantly smaller total corpus callosum, genu, posterior body, and isthmus areas compared with right-handed healthy control subjects (analysis of covariance with age, gender, and intracranial volume as covariates, p <.05). Partial correlation analyses, controlled for intracranial volumes, found a significant inverse relationship between age and total callosal, genu, anterior body, isthmus, and circularity in healthy control subjects (p <.05) but not in bipolar patients (p >.05). CONCLUSIONS: Smaller callosal areas may lead to altered inter-hemispheric communication and be involved in the pathophysiology and cognitive impairment found in bipolar disorder.