examined the association of personality traits with cocaine or heroin use. As expected in a population-based sample, we also found substantial overlap among the other drugs used. Of the former and current smokers, 52% had also used marijuana, 21% cocaine, and 8% heroin. About 78% of current and former marijuana users had also smoked cigarettes, 40% had used cocaine, and 15% heroin. About 82% of current and former heroin/cocaine users had also smoked cigarettes and 98% had used marijuana. Demographic information by drug type is given in Table 1: Across substances, current users were younger; males were more likely to use marijuana and cocaine/heroin, but there were no sex differences in cigarette smoking; African-Americans were more likely to use substances; and low education was associated with higher use of substances, with the exception of marijuana.
