Shared and Distinct Alterations in Brain Connectivity and Cognitive Function in Subthreshold and Major Depression

Motivation: Subthreshold depression (StD) is considered a prodromal stage of major depressive disorder (MDD), which often results in misdiagnosis and delays in proper treatment. Goal(s): This study aims to investigate the neurobiological mechanisms of StD by analyzing functional connectivity (FC) and cognitive function in comparison to MDD. Approach: Whole-brain FC was calculated using seeds from 4 network and cognitive function was assessed of 153 StD individuals, 188 MDD patients and 110 healthy controls (HCs). Results: StD showed social cognition deficit and dysfunction of the salience network(SN) and affective network(AN). MDD showed multi-domain impairments and dysfunction of the SN and AN and default model network. Impact: Abnormal SN/AN connectivity may cause depressive symptoms in StD/MDD. Altered DMN FC may trigger disease onset. StD first shows social cognition deficit linked to SN.