Examining Mu Opioid Mechanisms of Ketamine's Rapid Effects in OCD (MKET2)

Eligibility Criteria for Participants with OCD:

Inclusion Criteria:

• Ages 18-65

• Meet the criteria for OCD diagnosis

• Failed at least 1 prior trial of standard first-line OCD treatment

• Agree to the following lifestyle modifications: comply with requirements for fastingprior to the Experimental Session, not enroll in any other interventional clinicaltrials during the duration of the study, and commit to medication study procedures.

• Able to provide informed consent

Exclusion Criteria:

• prior naltrexone or ketamine use/exposure

• Any current or past medical/psychiatric condition that makes participation unsafe inthe opinion of the investigator or study physician

• Pregnant or nursing, or able to become pregnant and are not practicing an effectivemeans of birth control

• the presence of metal in the body that is contraindicated for MRI scans

Eligibility Criteria for Healthy Volunteers:

Inclusion Criteria:

• Ages 18-65

• Able to provide informed consent

Exclusion Criteria:

• current or past use of psychotropic medication

• pregnant or nursing females

• the presence of metal in the body that is contraindicated for MRI scans