Drawing upon an “exposure opportunity” concept described by Wade Hampton Frost, the
authors studied two mechanisms to help account for prior observations about the “stepping …

The earliest stages of involvement with illicit drugs have been understudied. In a recent
report, we examined initial opportunities to try marijuana and transitions from first opportunity …

Aims Strong associations between marijuana use and initiation of hard drugs are cited in
support of the claim that marijuana use per se increases youths' risk of initiating hard drugs …

Prior research based on representative samples drawn from the general population
suggests persons tend to follow a common developmental pathway from use of alcohol as …

We examined three components of the “gateway theory” in relation to marijuana use:(1)
whether adolescent marijuana use predicts young adult drug use,(2) whether this …

ADEVELOPMENTAL SEQUENCE OF INVOLVEMENT IN drugs is one of the best replicated
findings in the epidemiology of drug use. Regular sequences and stages of progression in …

Possible linkages of influence among classes of drugs in the observed sequential
progression from adolescence to young adulthood are investigated through event history …

Sequence of drug use was examined in a secondary analysis of two samples of serious
drug users: one of 152 men and one of 133 women. The proportions of drug users following …

Objective: The authors investigated whether the transition from licit drug use to marijuana
use is determined by particular risk factors, as specified by the gateway hypothesis. They …

The prevalence of last year use of alcohol, cigarettes, marijuana and cocaine in the US
population and conditional prevalence of a proxy measure of last year dependence among …