 This study evaluates theories regarding cocaine abstinence which propose that increased presynaptic and postsynaptic dopamine activity and increased serotonin activity are associated with abstinence in cocaine dependent subjects at the beginning and three to six months after a treatment program. We are using positron emission tomography PET, Magnetic Resonance Imaging MRI and diffusion tensor imaging DTI in cortical and subcortical areas in a series of brain imaging studies testing these theories of abnormalities in the dopamine and serotonin system for cocaine addiction by examining the distribution of 18F-fallypride, 18F-altanserin, and FDG. We are evaluating genetic theories associated with cocaine addiction through the examination of genetic markers and functional genomics. 