Efficacy of Treatment With Pramipexole or Risperidone in Patients With Refractory Obsessive-compulsive Disorder (OCD)

Inclusion Criteria: 1. Age between 18 and 64 years; 2. European Portuguese as mother tongue; 3. Patients diagnosed with OCD, regardless of subtype, according to DSM-5 and/or ICD-10 criteria; 4. Yale-Brown Obsessive Compulsive Scale (Y-BOCS) score ≥ 16; 5. Patients who do not respond to treatment with at least two selective serotonin reuptake inhibitor antidepressants (SSRIs) at the maximum tolerated therapeutic dose with or without psychotherapy, i.e. patients in whom there is no reduction in the Y-BOCS score by 25% to 35% relative to the score obtained before starting treatment with SSRIs (Rauch \& Jenike, 1994). Exclusion Criteria: 1. Patients who have a complete response to drug treatment with or without psychotherapy, i.e. patients with a reduction in Y-Bocs score by 25% to 35% regarding the score obtained before starting treatment with SSRIS (Rauch \& Jenike, 1994); 2. Patients with current or anterior history of psychotic illness (schizophrenia, delusions, among others); 3. Patients with bipolar disorder; 4. Patients with tick disorder; 5. Patients with borderline personality disorder; 6. Patients with social anxiety disorder; 7. Patients with current or anterior history of dietary behavior disorders (at least in the last 6 months); 8. patients with a history of neurological disease or traumatic brain injury; 9. Patients with history of alcohol abuse or illicit substances (at least in the last 6 months); 10. patients who are passing or have passed in the last 6 months by a major depressive episode; 11. Patients that undergo deep brain stimulation; 12. Presence of sensory deficits impeding participation in clinical study; 13. Pregnant or in breastfeeding period; 14. Patients doing medication or receiving prohibited treatments; 15. Patients with contraindication to perform MRI.