NCT01730781 · Yale University
Imaging Cannabinoid Receptors Using Positron Emission Tomography (PET) Scanning
What this study is about
The aim of the present study is to assess the availability of cannabinoid receptors (CB1R) in the human brain. CB1R are present in everyone's brain, regardless of whether or not someone has used cannabis.
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The aim of the present study is to assess the availability of cannabinoid receptors (CB1R) in the human brain. CB1R are present in everyone's brain, regardless of whether or not someone has used cannabis. The investigators will image brain cannabinoid receptors using Positron Emission Tomography (PET) imaging and the radioligand OMAR, in healthy individuals and several conditions including 1) cannabis use disorders, 2) psychotic disorders, 3) prodrome of psychotic illness and 4) individuals with a family history of alcoholism, 5) Post-Traumatic Stress Disorder 6) Opioid Use Disorder using the PET imaging agent or radiotracer, \[11C\]OMAR. This will allow us to characterize the number and distribution of CB1R in these conditions. It is likely that the list of conditions will be expanded after the collection of pilot data and as new data on cannabinoids receptor function and psychiatric disorders becomes available. Those in the cannabis us disorder arm of the study will have a PET scan on at least three occasions: once while smoking as usual, once after 48-hours of abstinence from cannabis, and a final time after 4 weeks of abstinence. Additional scans may be conducted within the 4 weeks and the last scan may be conducted well beyond 4 weeks. Similarly, while most schizophrenia patients may get scanned just once, a subgroup of patients may get scanned more than once. For example to tease out the effects of medications, unmedicated patients may get scanned while unmedicated and again after treatment with antipsychotic medications. Similarly prodromes may get scanned while in the prodromal stage off medications, on medications and after conversion to schizophrenia.
Interventions
RADIATION
[11-C]OMAR
The radiotracer, \[11-C\]OMAR will be administered at no more than 10 micrograms at the beginning of each PET scan.
Primary outcome measures
PET Imaging
Time frame: One time within 4 weeks of screening
This study will utilize the radioligand \[11C\]OMAR and High Resolution Research Tomography (HRRT) Positron Emission Tomography (PET) to measure brain CB1 receptor availability in all study populations. Those in the cannabis dependent population of the study will have PET scanning on three occasions: once within four weeks of screening while smoking as usual, once 48-hours later after remaining abstinent, and once four weeks later after remaining abstinent. The change in receptor density at each time point will be evaluated. Those in the other populations will have PET scanning done on one occasion within four weeks of screening.
Who can participate
This study lists these criteria on ClinicalTrials.gov. A study coordinator reviews eligibility during screening — this page does not determine whether you qualify.
Inclusion criteria
- Males ages 18-55
- For cannabis users:
- Willing to abstain from cannabis use for four weeks
- For schizophrenia:
- Meets DSM-IV-TR criteria for schizophrenia or schizoaffective disorder
- For prodrome for psychotic illness:
- Meets SIPS criteria for prodromal syndrome
- For family history positive:
- First degree relative with alcoholism
- For Post-Traumatic Stress Disorder
- Meets DSM-IV-TR criteria for PTSD
- Meets DSM-IV-TR criteria for Opioid Use Disorder
Exclusion criteria
- Current neuro-psychiatric illness (including cannabis dependence) or severe systemic disease. Cannabis use disorder is permitted in the cannabis dependent group. Schizophrenia and schizoaffective disorder is permitted in the schizophrenia group. Psychotic symptoms are permitted in the prodromal group. Post-Traumatic Stress Disorder is permitted in the PTSD group and Opioid Use Disorder is permitted in the OUD group.
- Presence of ferromagnetic metal in the body or heart pacemaker
- Have had exposure to ionizing radiation that in combination with the study tracer would result in a cumulative exposure that exceeds recommended exposure limits
- Are claustrophobic
Where
- New Haven, Connecticut
Collaborators
National Institute on Drug Abuse (NIDA), National Institute of Mental Health (NIMH)
Related conditions & keywords
Frequently asked questions
What is a clinical trial?
A clinical trial is a research study that tests new medical treatments, drugs, devices, or procedures to determine their safety and effectiveness. Trials are carefully designed and monitored to protect participants while advancing medical knowledge.
Is it safe to participate?
Clinical trials follow strict safety guidelines and ethical standards. Trials must be reviewed and approved, and participants are closely monitored by medical professionals throughout the study. You can withdraw at any time if you choose.
Will I be compensated?
Many clinical trials offer compensation for your time, travel expenses, and inconvenience. The specific compensation varies by study and will be discussed during the screening process. All study-related medical care is typically provided at no cost to participants.
Will I receive a placebo instead of treatment?
When effective treatment exists, participants typically receive either the standard treatment plus the study intervention, or the standard treatment plus placebo. You would not be denied effective care. Placebos are primarily used when no proven treatment is available, or in addition to standard care. Your trial consent form will clearly explain what treatments you may receive.
Can I leave a trial if I change my mind?
Absolutely. Participation in clinical trials is completely voluntary. You have the right to withdraw from the study at any time, for any reason, without penalty or loss of benefits to which you are otherwise entitled.
How long does a clinical trial last?
Trial duration varies widely depending on the study design and purpose. Some trials last just a few weeks, while others may continue for months or years. The study coordinator will provide specific timeline information during your screening call.
Data: ClinicalTrials.gov · synced Apr 27, 2026 · Source of record for eligibility and locations