ECT Increases Hippocampal Growth, But What Does That Mean?

Electroconvulsive therapy (ECT) has been found to induce increases in hippocampal size (NEJM JW Psychiatry Mar 2016 and Biol Psychiatry 2015; 79:282). To explore whether this finding is related to ECT's therapeutic effect in depression, researchers performed magnetic resonance imaging scans on 281 depressed patients before and after a course of ECT in a multisite study; for comparison, 95 healthy controls were neuroimaged twice. Most ECT patients were also taking antidepressants.

Hippocampal volume increased in patients with ECT but not over time in controls. Larger increases in hippocampal volume were associated with more ECT sessions so that patients whose depression improved more required fewer ECTs and had less hippocampal enlargement. I…