ECT is a highly effective treatment for MDD; however, relapses are a major concern. To prevent relapse in patients who have responded to ECT, the common treatment is antidepressants as continuation therapy (following the initial therapy in order to continue treating the disorder). Relapses, however, can still occur even after antidepressant continuation therapy. This study will evaluate a potent antidepressant combination in order to prevent relapse. C-ECT is another option that needs to be tested.