H-coil high-frequency deep transcranial magnetic stimulation (dTMS) over the medial prefrontal cortex (mPFC) and anterior cingulate cortex (ACC) has been approved by the Food and Drug Administration for use in treatment-resistant obsessive-compulsive disorder. At the same time, there are studies in the literature showing the effectiveness of intermittent theta burst stimulation application and the advantages of short treatment duration. However, there is no strong scientific evidence yet on the effectiveness and safety of iTBS (50 Hz) application with a double-cone coil in obsessive-compulsive disorder patients. The aim of this study is to evaluate the effectiveness of dTMS with ITBS protocol on the medial prefrontal cortex (mPFC) and anterior cingulate cortex (ACC) in OCD patients.

The current study aimed to investigate the effectiveness and safety of the ITBS protocol, which is applied to the mPFC and ACC for 5 sessions per day with a double-cone coil in treatment-resistant OCD patients. This study evaluated (I) the effectiveness of Itbs (50 Hz) stimulation of the mPFC and ACC with a double-cone coil and (II) the effectiveness of administering this protocol over 2 weeks rather than six weeks as approved by the FDA. Participants will be randomized into two parallel groups in a double-blind manner. In one group, ITBS (50 Hz) dTMS will be applied to mPFC and ACC, and in the other group, sham tms will be applied to the same regions. The application consists of a total of 50 sessions, 5 times a day. This application will last for a total of 10 days excluding weekends.

Inclusion Criteria:

• Clinical diagnosis of obsessive-compulsive disorder
• Not having an adequate response to treatment despite the use of an SGI selective serotonin reuptake inhibitors at a sufficient dose and duration (at least 8 weeks) before the planned add-on treatment
• No dose or active substance changes have been made in the treatment regimen for at least 8 weeks
• Aged 18-65 years
• Able to read and write
• Not having a significant medical or neurological disease

Exclusion Criteria:

• Not providing consent to participate in the study
• Diagnosis of a psychiatric disorder, such as psychotic disorder, bipolar disorder, major depressive disorder [Hamilton Depression Rating Scale (HDRS) score above 17], mental retardation, alcohol-substance use disorder, and organic mental disorder (dementia, delirium, and head trauma, etc.)
• Diagnosis of an important medical or neurological disease (e.g., epilepsy);
• Mental retardation
• Illiteracy
• Having received electroconvulsive therapy (ECT) or TMS within the last six months;
• Having any prosthesis, such as an implant and pacemaker.