Transcranial Magnetic Stimulation and Psychotherapy for Treating Obsessive-Compulsive Disorder

rTMS will be delivered with the MagPro X100 system equipped with a Cool-DB80 coil and a Localite neuronavigation system. Neuronavigation will be performed for anatomical landmarking and co-registration of the brain to Talairach stereotaxic space, with the co-registered coil vertex coordinate (x0, y+60, z+60) as performed in previously published work on dmPFC-rTMS and which represents \~25% of the nasion-inion distance. Posterior coil handle orientation will be used with stimulation parameters of 20Hz repetition rate, 2 second stimulation duration, 20 second inter-train interval, and 50 trains, for a total of 2000 pulses per day. Stimulation will be delivered at 100% of extensor hallucis longus muscle resting motor threshold (MT), as determined by the PI. rTMS will be delivered 5 days per week (Monday through Friday) for 6 weeks for a total of 30 treatment sessions, in keeping with established protocols. Trained research staff will perform daily rTMS treatments and monitor participants.

Supportive therapy (ST) is a nondirective "talk therapy" focused on enhancing coping skills, strengthening existing resources, and improving daily functioning. Core techniques will include active listening, encouragement, validation, reframing, clarification (summarizing and paraphrasing), and naming problems. Participants will receive two ST sessions per week during the 6-week rTMS course. General goals include using the therapeutic relationship to foster adaptation, improve self-esteem, and support overall well-being. Each session will last 53-60 minutes and take place concurrently with rTMS, with the participant remaining in the TMS treatment room throughout.

ERP is a form of cognitive-behavioral therapy designed to reduce obsessive-compulsive symptoms by weakening the association between feared stimuli and maladaptive responses. It promotes the formation and recall of non-threatening associations to counter fear-based learning. The participant and therapist will collaboratively create a hierarchy of OCD triggers, rated using the Subjective Units of Distress Scale (SUDS). ERP will begin with exposures rated 4-7 on the SUDS, while participants refrain from engaging in compulsions. Each trigger will be repeated until the SUDS rating decreases by at least 50% before progressing to the next item. Between-session ERP homework will be assigned, and participants will be provided self-monitoring homework rating forms to complete for subsequent review with the therapist. Each ERP session will last 53-60 minutes and will be conducted concurrently with rTMS, with the participant remaining in the TMS treatment room throughout.