A total of 73 postmortem brain specimens were obtained from two separate resources of known drug abusers and respective controls that were separately evaluated in Study I (n = 29) and Study II (n = 44). Study I, defined here as a multidrug population, represents three groups of drug abuse subjects — heroin, cocaine, heroin-cocaine. Study II represents a group of heroin abusers. The subjects had a documented history of abuse, but no posthumous DSM-IV dependence diagnosis was assigned as it was not possible to fully characterize the behavioral pattern of the subject's drug use during life.
