Two studies are proposed. The first study concerns the affective and cognitive consequences of ECT in 160 patients presenting primary, major depressive disorder. Patients will be randomly assigned to four ECT treatment conditions, crossing the factors of low and high ECT dosage and modality (unilateral right and bilateral electrode placements). Treatment responders will enter a double-blind drug continuation trail, contrasting nortriptyline and placebo. At pretreatment, postsixth ECT, posttreatment and 2-month followup a battery of clinical neuropsychological, neurophysiological, and neuroendocrinological procedures will be administered. Acute cognitive effects will also be examined at each treatment. Normal controls will be tested on major portions of the battery. The primary aims are (1) to determine dose/response relations as a function of modality for the affective and cognitive consequences of ECT (2) to identify pretreatment lateralized abnormalities in depressives and the effects of treatment conditions on such abnormalities (3) to determine the risk/benefits of postECT continuation medication in patients largely medication resistant during the acute phase of illness. The second study concerns the treatment of acute manic episodes. Patients (n=120) will be randomly assigned to intensive pharmacotherapy with combination lithium/neuroleptic treatment or to unilateral left, unilateral right, or bilateral ECT conditions, after establishing resistence to preentry pharmacotherapy. Treatment responders will enter a double-blind comparison of low (0.5-0.7mEq/L) and high (0.8-1.OmEq/L) lithium continuation/maintenance therapy. The primary aims are (1) to determine rates of therapeutic response to the four acute treatments conditions, with the hypothesis that the ECT conditions will be more efficacious than intensive pharmacotherapy and that among the ECT conditions, left and bilateral ECT will be superior in efficacy to unilateral right ECT, (2) to identify neurophysiological abnormalities in regional cerebral blood flow and brain electrical activity in acute manic episodes and the effects of treatment conditions on such abnormalities, (3) to contrast low and high dosage lithium conditions with respect to quality of remission and rates of relapse/recurrence.