Structural brain differences in major depressive disorder patients with suicidal risk: Evidence from the DIRECT...

Although previous studies have reported structural brain alterations in major depressive disorder (MDD) patients at risk of suicide, no wide consensus has been reached. This study aimed to elucidate structural brain differences between MDD patients with and without suicide risk using data from the DIRECT Consortium, advancing our understanding of the neurophysiological mechanisms underlying suicide risk in MDD patients.

A total of 203 healthy controls (HCs), 208 MDD patients without suicide risk (MDD-NSR), and 376 MDD patients with suicide risk (MDD-SR) were included. T1-weighted MRI data were processed using DPABISurf to quantify cortical surface area, thickness, and cortical gray matter (CGM) volume.

The MDD-SR and MDD-NSR groups demonstrated reduced surface area in the right orbitofrontal cortex (OFC), and reduced CGM volume in the left ACC and the right OFC compared with the HC group. The left ACC CGM volume decreased in a gradient, with the MDD-SR group showing significantly lower values than both the MDD-NSR and HC groups. While the SVM model showed limited differentiation between MDD-SR and MDD-NSR, the left ACC CGM volume was identified as the most critical feature in SHAP analysis.

MDD patients with suicide risk exhibited alterations in cortical surface area and CGM volume in the frontal lobe. The CGM volume reduction in the left ACC may serve as a potential biomarker for predicting suicide risk in MDD patients.