Intermittent administration of low dose ketamine can shorten the course of electroconvulsive therapy for depression and reduce complications: A randomized controlled trial

•This study aimed to investigate the efficacy and safety of intermittent low-dose ketamine on improving the efficacy of ECT.•The results showed that low-dose ketamine (0.3mg/kg) in combination with ECT treatment can improve the remission rate of depression.•Intermittent and repeated adjunctive administration modes of ketamine have the same effect on improvement of ECT.•The intermittent administration of ketamine reduced the occurrence of psychiatric complications. This study aimed to investigate the efficacy and safety of intermittent low-dose ketamine on improving the efficacy of ECT. Patients diagnosed with Major Depressive Disorder (MDD) (n = 134) were randomized into 3 groups: routine ECT group (group E, n = 45); repeated ketamine-assisted ECT group (group RK, n = 43), and intermittent ketamine-assisted ECT group (group IK, n = 46). Patients in group RK were given ketamine at the dose of 0.3 mg/kg for each ECT treatment, patients in group IK were given ketamine once a week during ECT course. The depressive symptoms were assessed using the Hamilton Depression Rating Scale (HAM-D) at baseline, the end of ECT course, after 1 and 3 months, followed by an analysis of the psychiatric complications. Results indicated that ketamine-assisted ECT achieved a higher remission rate (P