Who becomes cannabis dependent soon after onset of use? Epidemiological evidence from the United States: 2000-2001.

In this paper we estimate the risk of becoming cannabis dependent within 24 months after first use of cannabis and examine subgroup variation in this risk. The study estimates are based on the National Household Survey on Drug Abuse conducted during 2000-2001, with a representative sample of U.S. residents ages 12 and older (n=114,241). A total of 3352 respondents were found to have used cannabis for the first time within a span of up to 24 months prior to assessment. An estimated 3.9% of these recent-onset users developed a cannabis dependence syndrome during the interval since first use (median interval duration approximately 12 months). Excess risk of cannabis dependence was found for those with cannabis onset before late-adolescence, those with family income less than US dollars 20,000, and those who had used three or more drugs before the first use of cannabis (i.e., tobacco, alcohol, and other drugs). While these findings generally support previous study results, this study's focus on recent-onset users more closely approximates prospective and longitudinal research on the incidence (risk) of becoming cannabis dependent soon after onset of cannabis use, removing the influence of users with long-sustained or persistent cannabis dependence developed years ago.