Electroconvulsive therapy regulates brain connectome dynamics in patients with major depressive disorder

BACKGROUND Electroconvulsive therapy (ECT) is an effective treatment for patients with major depressive disorder (MDD), but its underlying neural mechanisms remain largely unknown. The aim of this study was to identify changes in brain connectome dynamics after ECT in MDD and to explore their associations with treatment outcome. METHODS We collected longitudinal resting-state fMRI data from 80 MDD patients (50 with suicidal ideation and 30 without; SI and NSI, respectively) before and after ECT and 37 age- and sex-matched healthy controls. A multilayer network model was used to assess modular switching over time in functional connectomes. Support vector regression was used to assess whether pre-ECT network dynamics could predict treatment response in terms of symptom severity. RESULTS At baseline, MDD patients had lower global modularity and higher modular variability in functional connectomes compared to controls. Network modularity increased and network variability decreased after ECT in MDD patients, predominantly located in the default mode and somatomotor networks. Moreover, ECT was associated with decreased modular variability in the left dorsal anterior cingulate cortex of MDD-SI, but not MDD-NSI patients, and pre-ECT modular variability could significantly predict symptom improvement in the MDD-SI group, but not in the MDD-NSI group. CONCLUSIONS We highlight ECT-induced changes in MDD brain network dynamics and their predictive value for treatment outcome, particularly in patients with suicidal ideation. This study advances our understanding of the neural mechanisms of ECT from a dynamic brain network perspective and suggests potential prognostic biomarkers for predicting ECT efficacy in patients with MDD.