Common and Distinct Patterns of Grey Matter Volume Alteration in Major Depression and Bipolar Disorder:Evidence from Voxel-Based Meta-Analysis

Finding robust brain substrates of mood disorders is an important target for research. The degree to which major depression and bipolar disorder are associated with common and/or distinct patterns of volumetric changes is nevertheless unclear. Furthermore the extant literature is heterogeneous with respect to the nature of these changes. We report a meta-analysis of voxel-based morphometry studies in major depression and bipolar disorder. We identified studies published up to January 2015 that compared grey matter in major depression (50 datasets including 4101 individuals) and bipolar disorder (36 datasets including 2407 individuals) using whole brain voxel-based morphometry. We used statistical maps from the studies included where available and reported peak coordinates otherwise. Group comparisons and conjunction analyses identified regions in which the disorders showed common and distinct patterns of volumetric alteration. Both disorders were associated with lower grey matter volume relative to healthy individuals in a number of areas. Conjunction analysis showed smaller volumes in both disorders in clusters in the dorsomedial and ventromedial prefrontal cortex, including the anterior cingulate cortex, and bilateral insula. Group comparisons indicated that findings of smaller grey matter volumes relative to controls in the right dorsolateral prefrontal cortex and left hippocampus, along with cerebellar, temporal, and parietal regions were more substantial in major depression. These results suggest that major depression and bipolar disorder are characterized by both common and distinct patterns of grey matter volume changes. This combination of differences and similarities has the potential to inform the development of diagnostic biomarkers for these conditions