For treatment-resistant major depression without psychosis, intravenous ketamine is at least as effective as electroconvulsive therapy (ECT). In a randomized trial with 403 patients, 55.4% of those receiving ketamine and 41.2% of those receiving ECT showed a 50% or greater reduction in depression scores over three weeks. ECT was linked to a notable decline in memory recall after three weeks (average decrease of 9.7 points on a memory test vs. 0.9 points with ketamine), with gradual recovery during follow-up. Quality-of-life improvements were similar between groups. Ketamine caused dissociation, while ECT led to musculoskeletal side effects.
In people with treatment-resistant depression who do not have psychosis, intravenous ketamine works as well as electroconvulsive therapy (ECT) overall. Among outpatients with moderately severe or severe depression, ketamine produced greater improvement in depressive symptoms than ECT. In contrast, inpatients with very severe depression improved more with ECT early in treatment, though by the end of the three-week course both treatments were similarly effective. Higher premorbid intelligence and a diagnosis of posttraumatic stress disorder were linked to greater improvement with ECT, but not with ketamine. These findings may help patients and clinicians decide between the two treatments.