Functional alterations of the medial frontal gyrus as candidate biomarkers for resilience in major depressive disorder

BACKGROUND: Major depressive disorder (MDD) is a prevalent psychiatric condition; however, candidate neural substrates related to resilience to MDD remain unclear. METHODS: Resting-state functional magnetic resonance imaging (fMRI) data were collected from 113 patients with MDD, 36 unaffected siblings, and 81 healthy controls (HCs). First, degree centrality (DC) analysis was performed to identify group differences. Next, regions showing significant DC differences were used as seeds for whole-brain functional connectivity (FC) analyses. Finally, associations between these significant brain regions and depressive symptom severity were examined separately within each participant group. RESULTS: DC in the medial frontal gyrus and the right precentral gyrus, as well as FC between the medial frontal gyrus and the right postcentral gyrus, exhibited the pattern: patients with MDD < HCs < unaffected siblings. Correlation analyses revealed no significant relationships between depressive symptom severity and DC or FC values. CONCLUSIONS: Unaffected siblings exhibited both the highest DC and the strongest FC related to the medial frontal gyrus. These neuroimaging findings provide further insight into the role of the medial frontal gyrus in potential resilience mechanisms and suggest potential directions for the prevention and treatment of MDD.