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.

NCT00816439

Conditions

1. Alcoholism

MeSH:Alcoholism

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.

Background: - The CB1 receptor is a protein in the brain that is targeted by the active ingredients in cannabis (marijuana). Brain systems that react to cannabis may be involved in the causes and symptoms of schizophrenia and schizoaffective disorder. For instance, research studies have shown that the number of CB1 receptors may be different in people with schizophrenia, and there may be differences in the receptors themselves. Researchers are interested in using positron emission tomography (PET) to study CB1 receptors in people with and without schizophrenia, using a chemical tracer that attaches specifically to CB1 receptors. Objectives: - To determine whether the CB1 receptor brain protein is different in people with and without schizophrenia. Eligibility: - Individuals between 18 and 55 years of age who either have been diagnosed with schizophrenia/schizoaffective disorder or are healthy volunteers. Design: - Participants in the study must have previously enrolled in the National Institute of Mental Health protocol A Neurobiological Investigation of Patients with Schizophrenia Spectrum Disorders and Their Siblings (95-M-0150). - Participants will provide blood samples to test for the gene that contains information on the specific type of CB1 receptor each participant has. - Participants will have a PET scan and/or a magnetic resonance imaging (MRI) scan. - The PET scan will last approximately 2 hours. Participants will receive an injection of a small amount of chemical tracer to improve the quality of the images taken during the scan. - The MRI scan will last approximately 1 hour.

NCT01063335

Conditions

1. Schizophrenia

MeSH:Schizophrenia

HPO:Schizophrenia

About half of the patients with schizophrenia 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.

Background: - Researchers have been studying behavioral components of nicotine addiction by looking at how drugs have a reinforcing effect, connecting the stimulation provided by the drug (nicotine) to the behavior that produces it (smoking). Based on previous studies, researchers are interested in learning more about how nicotine affects current smokers' responses to psychological tests and smoking-related cues, and in studying whether certain kinds of genetic background may affect smokers' responses to these kinds of studies. Objectives: - To compare the effect of nicotine versus denicotinized cigarettes during specific psychological tests. - To compare the effects of smoking cues versus neutral cues on craving, mood, and autonomic response. - To study the effect of genes on nicotine reinforcement and smoking-cue reactivity. Eligibility: - Individuals between 18 and 64 years of age who are current smokers (at least 10 cigarettes per day for at least 1 year) and are not currently interested in reducing their smoking or seeking treatment for tobacco dependence. Design: - Pilot session: - Participants will practice smoking using the measuring equipment that will be used in the study. - After successful practice, participants will read or listen to music for 1 hour, during which they are not allowed to smoke. - After the 1-hour period, participants will sample study cigarettes that have different levels of nicotine, and will be asked to guess whether the cigarettes are normal study cigarettes or denicotinized cigarettes. - Baseline session: - Blood, urine, and breath samples will be taken at the start of the session. - Participants will smoke part of an initial cigarette, and then will read or listen to music for 1 hour, during which they are not allowed to smoke. - After the 1-hour period, participants will give another breath sample and will complete questionnaires about mood and concentration levels. - Trial sessions: - Participants will smoke study cigarettes, and will be asked to either respond to questions about perceived nicotine levels in the cigarettes or press a lever for the chance to be rewarded with additional puffs of the cigarette. After the session, participants will give another breath sample and will complete questionnaires about mood and concentration levels. - Participants will also participate in cue-reactivity sessions to test the body's physiological response to smoking cues (a pack of cigarettes) and neutral cues (a pack of unsharpened pencils). After the session, participants will complete questionnaires on mood and concentration 15, 30, 45, and 60 minutes after the session. - At the conclusion of the last experimental session, participants will discuss the study with researchers, and may receive a referral list of smoking treatment programs.

NCT01505725

Conditions

1. Nicotine Dependence

MeSH:Tobacco Use Disorder

Genetic Measures The following genetic polymorphisms will be assayed: 1) C/T rs2023239 variant of the CB1R gene, 2) the Ser/Gly rs6280 variant of DRD3 gene, and 3) variants of the CYP2A6 gene.