Changes in the corpus callosum in women with late-stage bipolar disorder

Objective This study investigated the differences in corpus callosum (CC) volumes between women with early‐stage and late‐stage bipolar I (BP I) disorder using the criteria previously described in the literature. Method We compared women with early‐ and late‐stage BP I using criteria described in the Staging Systems Task Force Report of the International Society for Bipolar Disorders. We included 20 patients with early stage and 21 patients with late‐stage BP I and a group of 25 healthy controls. Patients and controls underwent structural magnetic resonance imaging. Information on the clinical features of bipolar disorder was collected using a standardized questionnaire. Anatomical volumes of five regions of CC were compared between the three groups. Results Women with late‐stage BP I disorder had reduced posterior CC volumes compared with early‐stage bipolar I patients and controls (F = 6.05; P = 0.004). The difference was significant after controlling for age, comorbidity with post‐traumatic stress disorder, psychotic symptoms during mood episodes, and current use of medication. Conclusion The posterior CC was significantly decreased in volume in women with late‐stage bipolar disorder. These findings suggest that CC may be an anatomical target of neuroprogression in the course of bipolar disorder in women.