Comparison of first-episode and multiple-episode bipolar disorder: A surface-based morphometry study

It is still unclear whether the structural abnormalities in Bipolar disorder (BD) are static or progressive. We aimed to compare differences in cortical thickness, surface area, and volume between patients with BD and healthy volunteers (HV) and to examine whether there are differences between patients who have had a single manic episode and those with multiple episodes. We recruited 30 patients with Type I BD and 30 age and sex matched HV. All participants underwent structural magnetic resonance imaging. Cortical volume, thickness, and surface area were measured using the QDEC tool from the Freesurfer software with age and intracranial volume as covariates. Study groups were comparable across age, sex distribution, and intracranial volume. Patients had significantly lower surface area in bilateral cuneus, right postcentral gyrus, and rostral middle frontal gyri; and lower cortical volume in the left middle temporal gyrus, right postcentral gyrus, and right cuneus. BD patients with multiple episodes had lower cortical measures while those with single episode had cortical measures comparable to HV. Findings indicate that the pathophysiological processes in BD are possibly progressive in nature. Our findings underscore the potential importance of early diagnosis and intervention in preventing deterioration and improving functional recovery.