The cannabinoid type 1 (CB1) receptor is a protein found in the brain that is involved with the effects of marijuana; it may also play a role in the effects of alcohol dependence and withdrawal. Earlier animal studies have shown that although long-term alcohol use decreases the number of CB1 receptors in the brain, the number returns to normal after alcohol use stops. This study will use positron emission tomography (PET) and magnetic resonance imaging (MRI) scans to trace a radioactive chemical called [11C]MePPEP, which can locate and measure the number of CB1 receptors in the brain. Researchers will study the CB1 receptors in the brains of people with alcohol dependence, and compare the results to the CB1 receptors in the brains of people without alcohol dependence. The results of this study will be used to further research into appropriate treatment procedures for alcohol dependence. This study will include 30 men with alcohol dependence and 50 men without alcohol dependence. All of the men must be between 18 and 65 years of age. Participants in both groups must not have any medical conditions that will prevent them from undergoing PET or MRI scans. For the PET scan, participants will be injected with a small amount of [11C]MePPEP and will then be brought to the PET scanner. The scan will take between 3 and 4 hours, but participants will be allowed to take breaks over the course of the scan. The MRI scan will not require any injections and will take approximately 1 hour to complete. Participants without alcohol dependence will make three visits to the National Institutes of Health Clinical Center. Blood and urine samples will be taken during one visit, and participants will arrange to have an MRI scan on one visit and a PET scan on the other visit, in whichever order they prefer. Participants with alcohol dependence will undergo two PET scans: the first will be performed between 3 and 7 days after the participant last consumed alcohol, and the second will be performed approximately 2 to 4 weeks after the first scan (with no alcohol consumption permitted in the interval). Participants will alcohol dependence will also undergo an MRI scan and will provide blood and urine samples.
There is one SNP
About half of the patients with alcohol dependence will be carriers of the C allele of the rs2023239 SNP and half will not.
About half of the healthy subjects will be carriers of the C allele of the rs2023239 SNP and half will not.