OCD is a chronic condition with a high rate of poor responders to conventional treatments, such as antidepressants and psychotherapy. Chronic symptoms can lead to important social impairment and suffering for patients and families.

The present study aims to investigate if the addition of transcranial magnetic stimulation can provide enhanced response to conventional treatment.

Transcranial magnetic stimulation is a noninvasive technique that can influence specific areas of the brain and has very few side effects.

The treatment with transcranial magnetic stimulation requires attendance to hospital daily sessions for 6 consecutive weeks. Each session lasts up to 30 minutes.

Side effects include scalp discomfort and mild headache. No anesthesia is required.

Stimulation aims the dorsolateral prefrontal cortex, a region previously studied to treat depression symptoms with positive results. The present technique has never been employed in previous studies, but risks are insignificant

Inclusion Criteria:

• resistant OCD patients: maximum 25% reduction in Yale-Brown Obsessive-Compulsive Scale (Y-BOCS) scores after at least 3 adequate trials with serotonin reuptake inhibitors (SRI) (including clomipramine) and 20 hours of cognitive behavioral therapy (CBT) or documented intolerance to either treatment.

Exclusion Criteria:

• metallic cerebral implants
• history of severe trauma or brain injury
• organic brain disease
• severe somatic disease
• history of drug dependence
• chronic psychosis
• present manic state