To investigate the treatment effect of repetitive transcranial magnetic stimulation on Obsessive-compulsive disorder, and the underlying neural mechanism by functional MRI.

All patients underwent a medical evaluation that included physical examination and routine laboratory studies before and after repetitive transcranial magnetic stimulation (rTMS) treatment. Patients were randomly allocated to rTMS group and the sham group. There are about 30 patients in each group. For the first 30 patients, allocation was by coin toss. For the subsequent 30 patients, allocation was according to computer generated random numbers. The decision to enroll a patient was always made prior to randomization. Patients were studied using a double-blind design. Study participants, clinical raters, and all personnel responsible for the clinical care of the patient remained masked to allocated condition and allocation parameters. Only rTMS administrators had access to the randomization list; they had minimal contact with the patients, and no role in assessing the Yale-Brown Obsessive Compulsive Scale(Y-BOCS). Each patient would be treated for continuous 15 days by rTMS.

Before the rTMS treatment, Y-BOCS, Padua Inventory-Washington State University Revision(PI-WSUR), Hamilton Depression Scale(HAMD-17) and Hamilton Anxiety Scale (HAMA-14) were obtained by a trained investigator to assess baseline severity of and other symptoms. The patients had receiving a battery measure of neuropsychological tests (standardized tests to investigate their cognitive problems, anxiety and depressive symptoms in daily life), magnetic resonance imaging scan in multimodalities, electroencephalography (EEG), event-related potentials during stop signal test and task switch paradigm record.

After the last treatment, Y-BOCS, PI-WSUR, HAMD-17 and HAMA-14 were obtained, as well as the Global Index of Safety to assess adverse events of the treatment. Patients were instructed to focus their answers on the past 15 days. The patients had also receiving a battery measure of neuropsychological tests, magnetic resonance imaging scan in multimodalities, and EEG record.

A month after the last treatment, participants were interviewed to obtain the Y-BOCS, PI-WSUR, HAMD-17 and HAMA-14. They were instructed to focus their answers on the past week. Additionally, they were also asked to assess the battery of neuropsychological tests, and have magnetic resonance imaging scan in multimodalities, and EEG record. Afterwards, they were unblinded by the study coordinator.

Inclusion Criteria:

Patients met diagnostic criteria for obsessive-compulsive disorder using The Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5)，confirmed by two clinical psychiatrist.

Y-BOCS total severity scores ≥16（Simple forced obsessions or compulsions ≥ 10），HAMA-14 scores < 14，HAMD-17 scores < 17； Raven's Standard Progressive Matrices（SPM） up to normal levels.

After more than one anti-OCD drugs treatment for 8-10 weeks, no significant improvement in symptoms.

Voluntarily participated and cooperated with the experiment.

Exclusion Criteria:

- History of significant head trauma or neurological disorders. Alcohol or drug abuse. Organic brain defects on T1 or T2 images. History of seizures or unexplained loss of consciousness. Family history of medication refractory epilepsy. recent aggression or other forms of behavioral dyscontrol.