Participants in this study must also be enrolled in NIMH protocol #98-M-0094 (SPECT Imaging of Dopamine and Serotonin Transporters in Neuropsychiatric Patients and Normal Volunteers) and protocol #91-M-014 (MRI Imaging of Neuropsychiatric Patients and Controls). Separate consent forms are required for each study. Candidates will undergo medical and psychiatric evaluations that may include blood and urine tests, electroencephalogram and electrocardiogram.