This proposal aims to test the hypotheses that hypothalamic stimulation is necessary for the relief of melancholia by electroconvulsive therapy; that the degree of baseline hypothalamic responsivity predicts the clinical response of melancholics to ECT; and, that the reported therapeutic advantage of bilateral over unilateral ECT in melancholia is a function of greater hypothalamic stimulation achieved with bilateral ECT. Serum prolactin (PRL) elevations will provide the measure of hypothalamic responsivity as obtained at baseline after intravenous protirelin and after each ECT during a course of treatment. Clinical improvement will be assessed by the Hamilton and Carroll rating scales for depression. Correlations will be examined between treatment response and two independent variables: the PRL response to the first ECT, and the difference between the PRL response to the first ECT and that to the sixth ECT, after entering as covariates age, initial severity of illness, PRL response to protirelin and treatment electrode placement. The long-term objective is to elucidate the mechanism of action of ECT in order to replace this therapeutic modality with one exhibiting fewer side effects, more specificity, and a greater asthetic acceptability.