Study Comparing Magnetic Seizure Therapy (MST) to Electroconvulsive Therapy (ECT) for Depression in Older Adults

To evaluate the feasibility, tolerability and efficacy of Magnetic Seizure Therapy (MST) in elderly patients with a major depressive episode, who are randomly assigned to receive an acute course of MST or ECT. The investigators hypothesize: 1. MST and ECT will have similar antidepressant efficacy 2. MST will have less post-treatment amnesia than ECT as reflected in a primary measures of anterograde and retrograde amnesia following the acute treatment phase. 3. At follow up, MST will show a lesser degree of persisting deficit in measures of retrograde amnesia than ECT.