Relationship of seizure duration to antidepressant efficacy in electroconvulsive therapy.

Background: A relationship between the anticonvulsant and antidepressant properties of electroconvulsive therapy (ECT) has been hypothesized. The goal of this study was to see whether the anticonvulsant effects of ECT could be measured in a clinical setting and whether there was any relationship between the anticonvulsant effects of ECT and the antidepressant response to it.

Methods: We examined the temporal relationship between change in seizure duration (as an index of anticonvulsant activity) and improvement in Hamilton Rating Scale for Depression scores in a retrospective sample of 114 depressed patients who received 145 courses of ECT. A linear mixed effects model was utilized for analysis so that the repeated measures nature of the data could be taken into account.

Results: Both seizure duration and depression scores decreased significantly through the course of ECT. However, no evidence was found for a relationship between decrease in seizure duration and clinical improvement as measured by Hamilton ratings.

Conclusions: The process underlying the reduction in seizure duration through a course of ECT may not be related to antidepressant efficacy.