Efficacy and safety of transcranial direct current stimulation as an add-on treatment for obsessive-compulsive disorder: a randomized, sham-controlled trial

Abstract

Obsessive-compulsive disorder (OCD) is a frequent, disabling disorder with high rates of treatment resistance. Transcranial direct current stimulation (tDCS) is a safe, tolerable noninvasive neuromodulation therapy with scarce evidence for OCD. This double-blind, randomized, and sham-controlled study investigates the efficacy of tDCS as add-on treatment for treatment-resistant OCD (failure to respond to at least one previous pharmacological treatment). On 20 consecutive weekdays (4 weeks), 43 patients with treatment-resistant OCD underwent 30 min active or sham tDCS sessions, followed by a 8 week follow-up. The cathode was positioned over the supplementary motor area (SMA) and the anode over the left deltoid. The primary outcome was the change in baseline Y-BOCS score at week 12. Secondary outcomes were changes in mood and anxiety and the occurrence of adverse events. Response was evaluated considering percent decrease of baseline Y-BOCS scores and the Improvement subscale of the Clinical Global Impression (CGI-I) between baseline and week 12. Patients that received active tDCS achieved a significant reduction of OCD symptoms than sham, with mean (SD) Y-BOCS score changes of 6.68 (5.83) and 2.84 (6.3) points, respectively (Cohen's d: 0.62 (0.06-1.18), p = 0.03). We found no between-group differences in responders (four patients in the active tDCS and one in the sham group). Active tDCS of the SMA was not superior to sham in reducing symptoms of depression or anxiety. Patients in both groups reported mild adverse events. Our results suggest that cathodal tDCS over the SMA is an effective add-on strategy in treatment-resistant OCD.

Figures

Fig. 1. CONSORT flow diagram for a study of transcranial direct current stimulation for the treatment of obsessive-compulsive disorder.

tDCS transcranial direct current stimulation, OCD obsessive-compulsive disorder. aThe analysis was performed in the intention-to-treat sample.

Fig. 2. Changes in the Mean Yale-Brown Obsessive Compulsive Scale (Y-BOCS) Score Over Time (tDCS group n = 22, sham tDCS n = 21).

tDCS transcranial direct current stimulation. Mean reduction in Y-BOCS scores in both treatment groups from baseline to week 12 (intention-to-treat analyses). Error bars indicate 1 SD.