Subanesthetic dose of ketamine for the antidepressant effects and the associated cognitive impairments of electroconvulsive therapy in elderly patients—A randomized, double‐blind, controlled clinical study

OBJECTIVES: We previously confirmed that low‐dose ketamine, as an adjunctive anesthetic for electroconvulsive therapy (ECT) in adult patients with depression, accelerates the effects of ECT and reduces the ECT‐induced learning and memory deficits. This study explored the efficacy and safety of low‐dose ketamine in elderly patients with depression. METHODS: Elderly patients with depression (N = 157) were randomly divided into two groups: propofol anesthesia group (group P) and propofol combined with ketamine anesthesia group (group KP). Patients in group KP were given low‐dose ketamine (0.3 mg/kg) for each ECT treatment; patients in group P were given the same amount of normal saline. Depressive symptoms and global cognitive functions were assessed using the 24‐item Hamilton Depression Rating Scale and Mini‐Mental State Examination, respectively, at baseline, 1 day after the 1st, 2nd, 4th, and 6th ECT sessions, and 1 day after the end of the ECT course. ECT effects of and complications were recorded. RESULTS: In total, 67 patients in group KP and 70 in group P completed the study. After the ECT, the response and remission rates were 82.09% and 73.13%, respectively, in group KP, and 81.43% and 68.57%, respectively, in group P; there was no statistical difference between groups. However, the incidence of cognitive function impairment was lower in group KP (10.4%) than in group P (25.7%), while different electrical dose and seizure duration were required during the course of treatment between the two groups. There was no difference in the complications of ECT between groups. CONCLUSIONS: Low‐dose ketamine is safe as an adjunct anesthetic for elderly patients subjected to ECT. It has a protective effect on cognitive function and may accelerate the antidepressant effects of ECT.