Obsessive-compulsive disorder (OCD) is a complex disorder with 40 to 60% of patients refractory to treatment. Developing alternatives to classical therapies would be helpful, and neuromodulation techniques offer promising perspectives. Theta-burst transcranial magnetic stimulation (TBS) has been shown to induce potent and long lasting effects on cortical excitability. Cortical inhibition of supplementary motor area (SMA) with low-frequency repetitive transcranial magnetic stimulation (rTMS) showed clinical benefits in OCD. The aim of the present study is to evaluate therapeutic efficacy and tolerability of continuous TBS (cTBS) over the SMA in treatment-resistant OCD patients using a double blind, sham-controlled design.

Thirty treatment resistant OCD outpatients (15 women and 15 men) were randomized to receive either active cTBS or sham cTBS for 6 weeks (5 sessions per week). Each treatment session consisted of 1800 stimuli at an intensity of 70% of resting motor threshold. Patients were evaluated at baseline, end of treatment (week 6), and follow-up (week 12). Response to treatment was defined as at least 25% decrease on the Yale–Brown Obsessive Compulsive Scale (YBOCS).

Treatment was well tolerated. However, there was no significant difference decrease in Y-BOCS scores, at baseline, weeks 6 and 12, between active and sham cTBS group. Responder rates were not different between groups at week 6 (cTBS 21% versus sham 36%; P=0.678) and week 12 (cTBS 29% versus sham 36%; P=1). Depressive and anxious symptoms improvement was also similar in the two groups.

This study is the first controlled trial using cTBS in OCD treatment refractory patients. Our results suggest that the use of cTBS over the SMA is safe but not sufficient to improve OCD symptoms. Further studies are needed to understand why cTBS is less efficient in reducing OCD symptoms compared to rTMS.