ECT Shows Greater Remission Rates in Bipolar Depression Than Unipolar Major Depression

Anees Bahji, MD

Electroconvulsive therapy (ECT), while unclear in its mechanism of action, is an effective therapy for depression, but has been—perhaps unfortunately—underutilized in mood disorder conditions such as bipolar depression (BD).

However, ECT has been shown to have not only similar response rates among patients with BD as it did for those with unipolar major depression (UP) but higher rates of symptom remission for those with BD.

Additionally, the therapy’s efficacy has not been historically compared between patients with BD and patients with UP. In a poster presentation at the American Psychiatric Association’s annual meeting in New York City, a group of researchers did just that.

The study, led by Anees Bahji, MD, from the department of psychiatry at Queen’s University, in Kingston, Ontario, Canada, included 17 of 40 articles for analysis of the 584 screened, the majority of which (n = 11) utilized bilateral ECT, while 10 included a unilateral ECT arm. In total, 23 articles were excluded from the study due to a lack of head-to-head comparison or lack of BD or UP groups.

The 17 studies included for the analysis reported on a variety of efficacy outcomes, including speed, response rates, remission, and hospital stay, with results measured by the Hamilton Depression Rating Scale (HAM-D), the Montgomery-Åsberg Depression Rating Scale (MADRS), or the Patient Health Questionnaire (PHQ9).

In total, the analysis included response rates for 1510 patients with UP and 491 patients with BD and remission rates for 913 patients with UP and 377 patients with BD.

The findings revealed a response rate of 58.9% (n = 889) for those with UP and 61.9% (n = 304) for those with BD, though the differences were not statistically significant (odds ratio [OR], 0.93; 95% CI, 0.73 to 1.2; P = .54).

Although, the rates of remission were 41.0% (n = 374) for those with UP, and 52.0% (n = 196) for those with BD, which was statistically significant (OR, 0.73; 95% CI, 0.56 to 0.96; P = .027).

Bahji and colleagues noted that “given the difficulties with traditional pharmacotherapy for BD,” the study findings may warrant increased use of ECT for patients with BD.

ECT’s antidepressant effect, while not completely understood, is related to neurophysiology changes from seizures induced by the treatment, including increased brain-derived neurotrophic factor and neurotransmitter receptor sensitivity. ECT is recommended for treatment-resistant depression, which includes conditions like BD and UP.

The study, “Efficacy of electroconvulsive therapy for unipolar vs. bipolar depression: a systematic review & meta-analysis,” was presented at the APA’s Annual Meeting on May 5, 2018.

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