Cannabinoid Medication for Adults With OCD

Cannabinoid Medication for Adults With Obsessive-Compulsive Disorder (OCD)

The purpose of this pilot research study is to test the effects of a medication called nabilone (Cesamet) in adults with obsessive-compulsive disorder (OCD). Participants will receive either nabilone on its own, or nabilone in combination with a form of cognitive-behavioral therapy (CBT) called exposure and response prevention (EX/RP). Nabilone is a synthetic cannabinoid and acts on the brain's "endocannabinoid system," which has been hypothesized to play a role in OCD. Nabilone is approved by the FDA for the treatment of chemotherapy-induced nausea and vomiting. It is not FDA-approved for treating OCD.

The two first-line treatments for OCD are a class of medications called serotonin reuptake inhibitors (SRIs) and a type of cognitive behavioral therapy called exposure and response prevention (EX/RP). But more than a third of patients with OCD do not respond to these treatments, and less then half become well. Thus, new treatment approaches are needed.

EX/RP is thought to involve fear extinction learning. Recent research suggests that modulators of the endocannabinoid system such as nabilone (a synthetic cannabinoid and agonist of the cannabinoid 1 receptor, CB1R) may enhance fear extinction learning and therefor could enhance EX/RP. However, nabilone could also work via modulating activity in cortico-striatal circuits, which contain high concentrations of CB1R, and thereby might reduce repetitive behaviors like compulsions seen in OCD.

To test both ideas, we will conduct a small pilot randomized trial to explore the effects of nabilone on its own for 4 weeks, vs. combined with EX/RP, in adult patients with OCD. This proof-of-concept study will investigate whether nabilone administration is feasible and well-tolerated in adult patients with OCD. The intent is to collect pilot data to support future grant applications.

Inclusion Criteria:

• Age 18-60
• Physically healthy, not pregnant
• Primary Obsessive-Compulsive Disorder (OCD)
• Patient off all psychotropic (except selective serotonin reuptake inhibitors [SSRIs]) and other types of drugs likely to interact with nabilone
• Ability to provide informed consent
• Ability to tolerate a treatment free-period

Exclusion Criteria:

• History of any significant medical condition that may increase the risk of participation
• Females who are pregnant or nursing
• Current or lifetime history of psychiatric disorders other than OCD that may increase the risk of participation (e.g. lifetime psychosis or bipolar disorder)
• Current substance use disorder or positive urine toxicology at screening, or any adverse reaction to a cannabinoid
• Patients already receiving EX/RP