Shared but distinct functional connectome profiles underlying rumination in depressed and healthy individuals.

BACKGROUND

Rumination—a passive, repetitive focus on negative thoughts and emotions—is a key risk factor for the onset and recurrence of depression. While prior studies have linked rumination to altered functional connectivity (FC) in brain networks, most relied on self-reported measures and resting-state fMRI, potentially missing key neural dynamics during active ruminative states.

METHODS

We recruited 43 patients with major depressive disorder (MDD) and 42 matched healthy controls (HCs). Using a validated rumination state task (RST), we induced active rumination and distraction states during fMRI scanning. We constructed whole-brain functional connectomes and examined both FC patterns and a graph-theoretical feature (eigenvector centrality) across conditions. We also examined associations between the graph-theoretical feature and depressive symptom severity.

RESULTS

Both MDD patients and HCs exhibited enhanced FC between the core and medial temporal lobe (MTL) subsystems of the default mode network (DMN) during rumination compared to distraction. However, edge-level analyses revealed group differences: HCs showed greater FC increases between the ventral attention network (VAN) and the DMN-MTL subsystem. We found a significant interaction effect regarding eigenvector centrality in a VAN node (Par_Med_4_R). During rumination, patients with MDD exhibited elevated eigenvector centrality compared to distraction, whereas HCs did not. This elevation correlated positively with depression severity.

CONCLUSIONS

This study provides the first comprehensive characterization of the active rumination connectome in MDD. Results highlight a shared DMN mechanism and a VAN-specific topological alteration in MDD, supporting the theory that excessive automatic constraints from attentional systems may drive maladaptive rumination. CLINICAL TRIAL NUMBER: Not applicable