This study’s finding that more women than men developed dependence on marijuana and opiates is at odds with findings from other DUI samples (Lapham et al., 2001), including one study reporting no gender differences in rates of drug dependence (Laplante et al., 2008), and a study reporting higher rates of hallucinogen dependence among males than females (Lapham et al., 2006). Because those studies did not condition drug dependence on drug use as we did in our analysis, we tested gender differences in our data a second time without conditioning on use and the gender differences remained significant. It is possible that women were more susceptible than men to the numbing effects of marijuana and opiates, given their higher endorsement of continuing to drink despite health and psychological problems.
