Comparison of corpus callosum area in bipolar disorder patients, their healthy siblings and healthy controls

ABSTRACT AIM: The aim of this study is to compare corpus callosum area patients with bipolar disorder, their healthy siblings who have similar genetic and environmental risk factors with patients; and healthy controls in order to test the risk of the disorder on the area of the corpus callosum. The aim of the 6-year follow-up was to compare changes in the corpus callosum in the patiens,, their healthy siblings, and control group. METHOD: Our study consists of two steps. At the first step of our study, the subjects (28 bipolar disorder patients, 28 healthy siblings and 38 healthy controls) who participated in the study named 'Brain regions associated with risk and resistance for bipolar disorder I disorder: a voxel-based MRI study of patients with bipolar disorder and their healthy siblings' were obtained with 3T magnetic resonance imaging (MRI). Corpus callosum area measurements were performed by ITK-SNAP software. We normalized the corpus callosum area by dividing the area to the intracranial volume for each subject. Data were assessed with analysis of variance (ANOVA). In the second step of our study, subjects who participated to the first step of the study were recalled after 6 years. All subjects were evaluated with SCID-I, Young Mania Rating Scale (YMRS) and Hamilton Depression Rating Scale-17 item (HAM-D-17). Subjects who met criteria our study (13 bipolar patients, 11 healthy siblings, 11 healthy controls) were obtained with 3 T MRI. Corpus callosum area measurements were performed with ITK-SNAP software. At 6-year follow-up the change in normalized corpus callosum areas between the groups was evaluated with repated measures ANOVA. RESULTS: In the first step of our study, patients with bipolar disorders had smaller normalized corpus callosum area than healthy controls. No significant change was observed between the groups in normalized corpus callosum area at 6-year follow-up. When measurements of each group were evaluated, no significant change in normalized corpus callosum area was detected in any of the groups. DISCUSSION: The first step of this study has a cross-sectional design and we found that the normalized corpus callosum area was smaller in patients with bipolar disorders than healthy controls. There were no difference in normalized corpus callosum areas between healthy controls and healthy siblings; therefore, these findings support the idea of smaller corpus callosum area is associated with the disorder itself. However, the fact that there was no difference in the callosal area between the groups in the 6-year follow-up study suggests that the changes in the corpus callosum are related to the treatment process, which helps the corpus callosum maturation to healthy levels in patients who continue their treatment. Keywords: Bipolar Disorders, Healthy Siblings, Magnetic Resonance Imaging, Corpus Callosum