ECT in bipolar and unipolar depression: differences in speed of response

Objectives: There is sparse evidence for differences in response to electroconvulsive therapy (ECT) between patients with bipolar or unipolar major depression, with virtually no information on speed of response. We contrasted a large sample of bipolar (BP) and unipolar (UP) depressed patients in likelihood and rapidity of clinical improvement with ECT. Methods: Over three double-blind treatment protocols, 228 patients met Research Diagnostic Criteria for UP (n=162) or BP depression (n=66). Other than lorazepam PRN (3 mg/day), patients were withdrawn from psychotropics prior to the ECT course and until after post-ECT assessments. Patients were randomized to ECT conditions that differed in electrode placement and stimulus intensity. Symptomatic change was evaluated at least twice weekly by a blinded evaluation team, which also determined treatment length. Results: Patients with BP and UP depression did not differ in rates of response or remission following the ECT course, or in response to unilateral or bilateral ECT. Degree of improvement in Hamilton Rating Scale for Depression scores following completion of ECT was also comparable. However, BP patients received significantly fewer ECT treatments than UP patients, and this effect was especially marked among bipolar ECT responders. Both BP I and BP II patients showed especially rapid response to ECT. Conclusions: The BP/UP distinction had no predictive value in determining ECT outcome. In contrast, there was a large effect for BP patients to show more rapid clinical improvement and require fewer treatments than unipolar patients. The reasons for this difference are unknown, but could reflect a more rapid build up of anticonvulsant effects in BP patients.