Characterization of CB1 Receptors Using [11-C]OMAR in Opioid Use Disorder

Characterization of CB1 Receptors Using [11-C]OMAR in Opioid Use Disorder

The goals of this sub-study is to assess CB1R availability in early abstinent individuals with OUD (following opioid agonist therapy - OAT stabilization) and in matched healthy controls.

Investigators will use PET imaging to investigate CB1R availability in treatment-seeking individuals with OUD during the early phase of OAT, compared to healthy controls (HCs). Using PET imaging with the CB1R-specific radioligand [¹¹C]OMAR, investigators will assess CB1R availability in predefined brain regions. Investigators will characterize group differences in CB1R availability, evaluate the relationship between CB1R alterations and negative emotional states, including mood, anxiety, and perceived stress, as well as risk of opioid relapse (defined as time to first use of non-prescribed opioids) over a 90-day follow-up period.

Inclusion Criteria:

All

• Normal screening bloodwork.
• Adequate arterial access for placement of an arterial line and blood sampling per study protocol.

OUD Participants:

• Diagnosis of opioid use disorder (OUD) according to DSM-5 criteria.
• Actively seeking treatment for OUD.
• Willingness to initiate opioid agonist therapy (OAT) with buprenorphine.

Healthy Controls:

• Good general physical health.
• No current or past diagnosis of any psychiatric or substance use disorders.

Exclusion Criteria:

All

• Any current major medical condition that, in the opinion of the Principal Investigator, poses a risk for PET procedures.
• Prior participation in research studies within the past year that would result in cumulative radiation exposure exceeding annual limits.
• Presence of ferromagnetic metal in the body, pacemaker, or other contraindications to MRI.
• Positive pregnancy test or current lactation.
• History of neurological conditions, including stroke or seizure disorders.
• Hematocrit values lower than 30

OUD Participants

• Current or past diagnosis of a serious psychiatric disorder.
• Current diagnosis of any substance use disorder other than nicotine or opioids.
• Use of any substances within the past 30 days.
• Current use of SSRIs or benzodiazepines or use within the past 30 days.
• Previous enrollment in the main study.

Healthy Controls:

• Current or past diagnosis of any psychiatric disorder.
• Current diagnosis of any substance use disorder (excluding nicotine).
• Use of any substances within the past 30 days.