Pre-supplementary motor network connectivity and clinical outcome of magnetic stimulation in obsessive-compulsive disorder.

A large proportion of patients with obsessive-compulsive disorder (OCD) respond unsatisfactorily to pharmacological and psychological treatments. An alternative novel treatment for these patients is repetitive transcranial magnetic stimulation (rTMS). This study aimed to investigate the underlying neural mechanism of rTMS treatment in OCD patients. A total of 37 patients with OCD were randomized to receive real or sham 1-Hz rTMS (14 days, 30 min/day) over the right pre-supplementary motor area (preSMA). Resting-state functional magnetic resonance imaging data were collected before and after rTMS treatment. The individualized target was defined by a personalized functional connectivity map of the subthalamic nucleus. After treatment, patients in the real group showed a better improvement in the Yale-Brown Obsessive Compulsive Scale than the sham group (F1,35  = 6.0, p = .019). To show the neural mechanism involved, we identified an "ideal target connectivity" before treatment. Leave-one-out cross-validation indicated that this connectivity pattern can significantly predict patients' symptom improvements (r = .60, p = .009). After real treatment, the average connectivity strength of the target network significantly decreased in the real but not in the sham group. This network-level change was cross-validated in three independent datasets. Altogether, these findings suggest that personalized magnetic stimulation on preSMA may alleviate obsessive-compulsive symptoms by decreasing the connectivity strength of the target network.