Manic episodes are associated with grey matter volume reduction - a voxel-based morphometry brain analysis

Objective: To investigate whether the lifetime number of affective episodes or illness duration is associated with changes in local grey matter volume, in patients with bipolar I disorder without comorbid conditions. Method: Magnetic resonance imaging scans of 55 patients with bipolar I disorder were analysed using VBM. Results: Smaller grey matter volume in the inferior frontal gyri of the dorsolateral prefrontal cortices (DLPFC) correlated significantly to the lifetime number of manic episodes. No association between local grey matter volume and the lifetime number of depression episodes or illness duration was found. Conclusion: We found strong evidence for a linear correlation between a decrease in DLPFC volume and the lifetime number of manic episodes in patients with bipolar I disorder. Interestingly, DLPFC is known to be important for executive functions and the findings in this study might hence be linked to the executive cognitive deficits associated with bipolar disorder.