Whole-brain Functional Connectivity Dynamics associated with Electroconvulsive Therapy Treatment Response.

BACKGROUND: Depressive episodes (DEP) characterized by abnormalities in cognitive functions and mood is a leading cause of disability. Electroconvulsive therapy (ECT), which involves a brief electrical stimulation of the anesthesia brain, is one of the most effective treatments used in patients with DEP due to its rapid efficacy.

METHODS: In this work, we investigated how dynamic brain functional connectivity responds to ECT and whether the dynamic responses are associated with treatment outcomes and side effects in patients. We applied a fully automated independent component analysis (ICA)-based pipeline to 110 patients with DEP (including diagnosis of unipolar depression or bipolar depression) and 60 healthy controls (HCs). The dynamic functional connectivity was analyzed by a combination of the sliding window approach and clustering analysis.

RESULTS: Five reoccurring connectivity states were identified, and DEP had fewer occurrences in one brain state (state 1) with strong positive and negative connectivity. DEP patients changed the occupancy of two states (states 3 and 4) after ECT, resulting in significantly different occurrences of one additional state (state 3) compared to HC. We further found that DEP patients had diminished global meta-state dynamism, two of which recovered to normal after ECT. Interestingly, the changes in dynamic connectivity characteristics were associated with the changes in memory recall and Hamilton Depression Rating Scale of DEP after ECT.

CONCLUSIONS: These converging results extend current findings on subcortical-cortical dysfunction and dysrhythmia in DEP and demonstrate that ECT might cause remodeling of brain functional dynamics that enhance the neuroplasticity of the diseased brain.