Brain Circuits in Schizophrenia and Smoking

Background: \- Smoking is associated with serious health risks. People who have mental illness are more likely to smoke. Researchers are studying the brain circuits linked with smoking and nicotine craving. This study will look at whether a specific brain circuit can explain the high rate of smoking in people with schizophrenia. Objectives: \- To study brain activity in smokers and nonsmokers with and without schizophrenia, as well as their family members. Eligibility: * Current smokers (at least 100 cigarettes in the past year) and nonsmokers between 18 and 62 years of age in one of the following groups: * Have been diagnosed with schizophrenia. * Family members of those with schizophrenia. * Healthy adults with no history of severe mental illness or brain trauma. * Family members of the healthy adults. Design: * People in the study will be screened with a physical exam, medical history, questionnaires, and blood tests. * They will have up to three visits: the screening visit and two study visits (each given 1 year apart). * At the first study visit, those taking part will be trained in the tests they will do during the magnetic resonance imaging (MRI) scan. Then they will have the MRI scan. * After the first study visit, current smokers will receive phone calls from the study researchers every other month for 1 year. They will be asked about their smoking habits. * At the second study visit, current smokers and some nonsmokers will have another MRI scan and the same tests as before. * Current smokers will receive a final phone call 1 year after the second study visit. They will be asked to give information about their smoking habits.