Comparative Study of Low-Dose Ketamine Infusion and rTMS in Treatment-Resistant Depression: A Posthoc Pooled Analysis of Two Randomized, Double-Blind, Placebo-Controlled Studies

SOURCE: Psychiatry Research. 316:114749, 2022 Oct.

AUTHORS: Chen MH; Cheng CM; Li CT; Tsai SJ; Lin WC; Bai YM; Su TP

BACKGROUND: This posthoc analysis compared the antidepressant and antisuicidal effects of low-dose ketamine infusion with those of repetitive transcranial magnetic stimulation (rTMS) on treatment-resistant depression (TRD).

METHODS: In the ketamine infusion trial, 48 patients with TRD were randomized to receive a single infusion of 0.5 mg/kg ketamine or normal saline. In the rTMS trial, 105 patients were randomly assigned to intermittent theta-burst stimulation (iTBS), 10-Hz rTMS, or sham stimulation. The 17-item Hamilton Rating Scale for Depression (HDRS) was administered.

RESULTS: The antidepressant effect was prominent at Day 7 postinfusion in the ketamine group but steadily accumulated with the treatment duration from Day 7 to 14 in the iTBS and 10-Hz rTMS groups, regardless of the level of treatment resistance (all p < .01). Low-dose ketamine infusion and iTBS exerted superior effects on suicidal symptoms (HDRS item 3) than the other three groups (p < .001). The antidepressant effect of iTBS/10-Hz rTMS may persist for up to 3 months; however, the antidepressant effect of a single low-dose ketamine infusion did not persist over a month.

DISCUSSION: Both low-dose ketamine infusion and rTMS/TBS must be included in TRD treatment but may be applied in different clinical situations.