Altered patterns of association between cortical thickness and subcortical volume in patients with first episode major depressive disorder: A structural MRI study

Depressed individuals may exhibit changes in cortical thickness and subcortical volume. However, we know little about their associated connection patterns in the brain's neural circuits. This study explored correlations between overall cortical thickness and the volume of several subcortical structures in first episode major depressive disorder (MDD) patients. Thirty-six untreated individuals experiencing their first episode of MDD were compared with healthy controls (n=41). Their brains were imaged by T1-weighted MRI, allowing the measurement of cortical thickness and the volume of subcortical structures. We found that in MDD patients, the cortex was thinner in four of the measured regions (frontal, temporal, parietal and insula) and the volume of the putamen and amygdala tended to be smaller compared with controls. Furthermore, the ratio of the volume of the four measured subcortical structures (left pallidum, left putamen, left amygdala and right caudate) to cortical thickness (measured in 11 regions)was significantly larger in the MDD group compared with controls. These results show that there are different relationships between subcortical volume and cortical thickness inearly-stage MDD and control subjects.