Speed of response to bilateral ECT: an examination of possible predictors in two controlled trials.

Speed of response to bilateral electroconvulsive therapy (ECT) was defined as the number of ECTs required to induce a 50% reduction in Hamilton Depression Scale score and was established in 48 patients who had participated in two controlled trials of twice versus three times weekly ECT and were responders to treatment. Potential clinical predictors of response were examined dichotomously by comparing early (up to and including ECT 4) and late (ECT 5-9) responders and by correlation. Younger patients manifested a more rapid response (p = 0.03), but no other clinical variables were significantly related to speed of response. Because speed of response affects choice of ECT schedule, biological predictors should be sought.