Predictors of marijuana use and uptake among teenagers in Sydney, Australia.

Information on drug-related behaviors was obtained from a random sample of teenagers aged 14 to 19 years in Sydney, Australia, interviewed in their homes in 1985 (N = 996) and 1986 (N = 756). The 1985 prevalence of current marijuana use was 10%. The predictors of marijuana use were: male sex; heavier, more frequent alcohol use; use of drugs other than alcohol, tobacco, or marijuana; marijuana use by siblings, friends, and other acquaintances; attitudes and beliefs favoring drug use; the attitude that possession of marijuana should not be a criminal offense; and the attitude that marijuana is not an important drug issue. In the 756 reinterviewed respondents, prevalence of marijuana use rose from 7% in 1985 to 9% in 1986. The rate of uptake was 6% and peaked at 12% at age 17. The predictors of uptake were: age; male sex; heavier, more frequent alcohol use; tobacco smoking; attitudes and beliefs favoring drugs use; and the attitude that marijuana smoking should be legal. Strategies to prevent marijuana use need to take into account the strong association between heavy drinking and marijuana use, the influence of drug users in the social network, and attitudes and beliefs about drugs.