A magnetic resonance imaging study of hippocampal, amygdala and subgenual prefrontal cortex volumes in major depression subtypes: melancholic versus psychotic depression.

Background: Volumetric studies examining brain structure in depression subtypes are limited and inconclusive. The aim of the current study was to compare the volumes of brain regions previously implicated in depression among patients with melancholic major depressive disorder (MDD), patients with psychotic MDD and normal controls.

Methods: Twenty two patients with melancholic MDD, 17 with psychotic MDD and 18 normal controls were included in the study. Hippocampal (HV), amygdala (AV), anterior (ASCV) and posterior (PSCV) subgenual cortex volumes were measured on magnetic resonance volumetric images.

Results: There were no volumetric differences between patients with melancholic and psychotic subgroups. We identified larger AVs and smaller left ASCVs in both patient groups compared to controls with medium to large effect sizes. Regression analysis revealed that AVs were predicted by the presence of depression, late depression-onset, insomnia and left hippocampal tail volume in patients, but not in controls. There were no differences in HVs, right ASCVs and PSCVs across the 3 groups.

Limitations: Small sample size, a possible inclusion of paracingulate gyrus in ASCV and PSCV tracings, significant differences in education level and medication status are discussed as limitations.

Conclusions: Diagnostically delineated melancholic and psychotic MDD patients do not differ in medial temporal and cingulate volumes. However, significant volumetric differences were detected between both patient-groups and controls.