Deep Brain Stimulation for Refractory Obsessive-Compulsive Disorder

Inclusion Criteria: * Patients with a diagnosis of obsessive-compulsive disorder according to Diagnostic and Statistical Manual of Mental Disorders (DSM) 5 criteria * Severe OCD assessed by the Yale-Brown Obsessive-Compulsive Scale (YBOCS) with a score of more than 27 * Refractory OCD; severe symptoms and impairment for more than 5 years despite pharmacological and psychological treatment. * Have failed to improve following treatment with at least two serotonin transport inhibitors and one augmenting agent taken for an adequate time period. * Having failed to improve despite adequate cognitive behavioral therapy, as evaluated by the study psychiatrist * Patients between 22 and 75. * Ability to understand and sign written informed consent by the patient. Exclusion Criteria: * Diagnosis of severe major depression disorder (MDD) with psychotic features. * Significant suicidal risk \[Hamilton Depression scale item 3 (suicide)\>2\]. * Comorbidity with any primary Psychotic Disorder, Post-Traumatic Stress Disorder (PTSD), or Eating Disorder. * History of substance or alcohol dependence or abuse in the preceding 12 months. * Significant cognitive decline, measured by Mini-Mental State Examination (MMSE \<26) and Montreal Cognitive Assessment (MoCA; \<24). * Any other current clinical significant neurological disorder or medical illness affecting brain function, other than a tic disorder. * Any clinically significant abnormality on preoperative MRI that would affect the safety of the surgical procedure in the opinion of the study neurosurgeon. * Any DBS contraindication, infection, coagulopathy, significant cardiac risk factors, or other medical risk factors for surgery. * Pregnancy.