This is a research study to find out if a new form of electroconvulsive therapy (ECT) is as effective and safe as a current form. The new form of ECT is called Frontal (Ultrabrief Right Unilateral) ECT. If enrolled in this this study, participants will be randomly assigned (like flipping a coin) to receiving Frontal ECT or the current standard form of ECT called Temporal (Ultrabrief Right Unilateral) ECT.

Depression is a very common disorder that is most often chronic or recurrent in nature. Many subjects do not respond adequately to an initial antidepressant treatment trial. Subjects who do not respond adequately to multiple therapeutic interventions are considered to have treatment-resistant depression (TRD). Among the treatment options for subjects with TRD is Vagus Nerve Stimulation (VNS) Therapy.This blinded, randomized, multicenter controlled study is intended to collect evidence that VNS Therapy as an adjunctive therapy improves health outcomes for patients with TRD.