Patient description: A 20 yo female college student with no significant past medical history presents with a chief complaint of fatigue. She reports increased sleep and appetite over the past few months as well as difficulty concentrating on her schoolwork. She no longer enjoys spending time with her friends and feels guilty for not spending more time with her family. Her physical exam and laboratory tests, including hemoglobin, hematocrit and thyroid stimulating hormone, are within normal limits.

Clinical trial eligibility criteria: eligible ages (years): 18.0-70.0,  Obsessive-Compulsive Disorder Meets DSM-IV-TR for a principal current diagnosis of OCD which is confirmed by both clinical evaluation and by structured interviews. OCD subjects with other comorbidities will be included provided OCD is judged to be the chief complaint Subjects must continue to experience clinically significant symptoms of OCD (Y-BOCS score ≥19 and a rating of "moderate" or greater on the Clinical Global Impressions (CGI) scale) despite at least two adequate SRI monotherapy trials. One unsatisfactory trial can the SRI currently being taken by the patient provided that the duration of treatment is 12 weeks or more and that the dose has been adequate. Subjects must be taking a clinically effective dose of a SRI (i.e., clomipramine, citalopram, escitalopram, fluoxetine, fluvoxamine, paroxetine and sertraline) for at least 12 weeks. Subjects must be on their current dose for at least 12 weeks and must maintain their current dose throughout the study Between the ages of 18-70 years of age Only subjects with OC symptoms of at least one-year duration will be included Eligible subjects must be in good physical health. Screening procedures will detailed medical history, complete physical and neurological exams, routine blood studies (CBC, liver function tests, electrolytes), ECG, urine toxicology screen, and serum pregnancy test in women of child-bearing potential  Primary depression, schizophrenia or other psychotic disorders Active bipolar disorder Non-responder in the past to atypical antipsychotic augmentation. This criterion was chosen to prevent recruiting a sample of chronically refractory OCD cases that would otherwise be suited for more extreme interventions such as deep brain stimulation Non-responder in the past to an adequate trial (> 20 hours) of cognitive-behavioral therapy that will be assessed by records review Current clinically significant suicidality or individuals who have engaged in suicidal behaviors within 6 months will be excluded and referred for appropriate clinical intervention Alcohol or other significant substance abuse within the last 6 months History of neurosurgery, encephalitis or significant head trauma or a significant medical condition such as heart, liver, or renal disease Nursing mothers or women of childbearing potential who do not use adequate contraception will be excluded Subjects at an increased risk for seizures will also be excluded from this study (e.g., subjects with a history of seizures [other than childhood febrile seizures], subjects taking concomitant medications known to lower the seizure threshold) Estimated IQ < 80, mental retardation, dementia, brain damage, or other cognitive impairment that would interfere with the capacity to participate in the study and complete measures. If needed, the WASI will be used to assess this at screening