• Obsessive compulsive symptoms [ Time Frame: Measured at Weeks 4 and 8 in Phase I and Weeks 12, 16, 20, 24, 28, and 32 in Phase II ] [ Designated as safety issue: No ]
  

• Social Adjustment Scale-SR [ Time Frame: Measured at Week 8 in Phase I and Week 32 in Phase II ] [ Designated as safety issue: No ]
  
• Quality of Life [ Time Frame: Measured at Weeks 4 and 8 in Phase I and Weeks 12, 16, 20, 24, 28, and 32 in Phase II ] [ Designated as safety issue: No ]
  

Obsessive-compulsive disorder (OCD) is a common psychiatric illness. People with OCD experience unwelcome thoughts, known as obsessions, and feel compelled to perform repetitive behaviors, or compulsions. Impairment due to OCD symptoms ranges from mild to severe, and sometimes can be disabling. The only medications proven effective for OCD are serotonin reuptake inhibitors (SRIs), but even with SRI treatment, most patients continue to experience significant OCD symptoms, impaired functioning, and diminished quality of life. Cognitive-behavioral therapy (CBT), a talking therapy that focuses on altering a person's thoughts and behaviors, and the medication risperidone have both been commonly used for augmenting SRI treatment for OCD. This study will compare the short- and long-term effectiveness of exposure and ritual prevention (EX/RP), a type of CBT, and risperidone in augmenting SRI treatment in people with OCD.

Participants in this double-blind study will be randomly assigned to receive EX/RP, risperidone, or placebo in conjunction with their regular SRI medication. All participants will remain on their regular SRI at a stable dose. During the first 2 months of the study, participants assigned to EX/RP will attend therapy sessions twice per week. In EX/RP, participants will be exposed to feared objects or ideas, and will be encouraged not to carry out a compulsive response. Participants assigned to risperidone or placebo will meet with a psychiatrist once every 1 to 2 weeks. At the end of 8 weeks, all participants' OCD symptom severity will be assessed. During this time, participants who have responded to treatment will continue receiving the same treatment for an additional 24 weeks. Participants assigned to EX/RP will meet with a therapist no more than 15 times total, and participants receiving risperidone or placebo will meet with a psychiatrist once every 4 weeks. Outcomes will be reassessed at study completion.