Serotonin Transporters in Alcoholism

Study Summary

This study will compare serotonin transporter proteins in people with alcoholism and healthy volunteers to examine how these proteins may be related to the inability of people with alcoholism to appropriately regulate their alcohol consumption. Serotonin transporters regulate levels of the brain chemical serotonin. Problems in this regulation have been implicated in alcoholism. Healthy normal volunteers and people who suffer from alcoholism who are between 18 and 75 years of age may be eligible for this study. Candidates are screened with a medical history and physical examination, psychiatric diagnostic interview, blood and urine tests, an electrocardiogram, urine toxicology screen, and written psychological evaluations. Participants undergo positron emission tomography (PET) and magnetic resonance imaging (MRI) scanning to measure serotonin transporter levels in the brain. PET uses small amounts of a radioactive chemical called a tracer that "labels" the serotonin transporters in the brain. The tracer used in this study is \[11C\]DASB. For the procedure, the subject lies on the scanner bed. A special mask is fitted to the head and attached to the bed to help keep the subject's head still during the scan so the images will be clear. A brief scan is done just before the radioactive tracer is injected. This scan provides measures of the brain that will help in the precise calculation of information from subsequent scans. After the tracer is injected through a catheter (plastic tube) placed in the arm, pictures are taken for about 2 hours. MRI uses a magnetic field and radio waves to produce pictures of brain structure. The subject lies on a bed that slides into the tube-like scanner, wearing earplugs to muffle loud noises the machine makes when the magnetic fields are switched. The scan takes about an hour, during which time the subject can communicate with the technician.