Lifetime history of alcohol use is nearly universal among adolescents and adults who have used cannabis (Degenhardt and Hall, 2003; Pape et al., 2009; Sartor et al., 2009). As might be expected, problem drinking also frequently co-occurs with cannabis dependence symptomatology: AD criteria are met by approximately 70% of individuals with cannabis dependence (Agosti et al., 2002; Stinson et al., 2006). Likelihood of developing cannabis dependence is similarly elevated in alcohol-dependent individuals: Degenhardt and Hall (2003) reported that the odds of meeting cannabis dependence criteria were 5.81 times higher in those who met criteria for AD than in those who did not. Many of the same risk factors associated with alcohol-related problems have also been linked to cannabis use and related symptomatology. For example, externalizing disorders, deviant peer affiliation and family history of substance use disorders are all well-documented correlates of problem use of both alcohol and cannabis (Elkins et al., 2007; Fergusson et al., 2002; Fergusson et al., 2008; Gillespie et al., 2009; Hayatbakhsh et al., 2008; Kuperman et al., 2001; Marshal et al., 2003; Monshouwer et al., 2006; Slutske et al., 1998), suggesting that the association may be attributable at least in part to common sources of risk.
