ECT-Induced and Drug-Induced Hypomania

In a retrospective chart study of 1,057 hospital admissions of endogenous depressives between 1920 and 1981, 139 patients (13%) had received electroconvulsive therapy (ECT), and 12% of them switched to hypomania. Within a subgroup of 524 psychotic unipolar depressives, 79 received ECT and eight (10%) switched to hypomania, whereas among those not treated with ECT only 16 of 445 patients (3.6%) switched to hypomania (p < 0.01). In psychotic bipolar patients the switch rates with and without ECT did not differ significantly (30% vs. 32%). Among untreated unipolar depressives hospitalized between 1920 and 1943, before the introduction of ECT or antidepressants, 3.9% switched to hypomania. Among unipolar patients admitted after 1957 and treated by antidepressants 4% switched to hypomania; among bipolar patients, 31% switched to hypomania. We find no evidence for hypomania being induced by standard antidepressants. Without classifying depressive patients into manic and nonmanic based on the previous history, studies of drug-induced hypomania cannot be conclusive. These observations strongly support the hypothesis of an ECT-induced switch from depression to hypomania.