Stages of progression in drug involvement from adolescence to adulthood: further evidence for the gateway theory.

TLDR

The study investigates sequential stages of drug involvement from adolescence to adulthood in a cohort followed from ages 15 to 35. Using this longitudinal cohort, the authors tested alternative progression models for goodness of fit. Four stages were identified—legal drugs/alcohol/cigarettes, marijuana, other illicit drugs, and medically prescribed drugs—and progression patterns differed by gender, with men’s illicit drug use depending on prior alcohol use and women’s marijuana use triggered by either cigarettes or alcohol, while earlier onset and higher frequency at lower stages strongly predicted further progression.

Abstract

Sequential stages of involvement in alcohol and/or cigarettes, marijuana, other illicit drugs and medically prescribed psychoactive drugs from adolescence to adulthood are investigated in a longitudinal cohort that has been followed from ages 15 to 35. Alternative models of progression are tested for their goodness of fit. Four stages are identified: that of legal drugs, alcohol or cigarettes; marijuana; illicit drugs other than marijuana; and medically prescribed drugs. Whereas progression to illicit drugs among men is dependent upon prior use of alcohol, among women either cigarettes or alcohol is a sufficient condition for progression to marijuana. Age of onset and frequency of use at a lower stage of drug use are strong predictors of further progression.