Adolescent precursors of intensity of marijuana and other illicit drug use among adult initiators.

This study examined (a) adolescent psychosocial risk factors for frequency (intensity) of marijuana use and for other illicit drug use among those who started using these drugs in early adulthood (adult initiators) and (b) the protective role of parent-adolescent relations in reducing or preventing drug use when adolescents enter early adulthood. The study's participants were male and female youth from a longitudinal prospective study. The participants' mean ages were 17 and 22 years at late adolescence and early adulthood, respectively. Independent measures assessed personality, parental, peer, and self-drug-use factors during late adolescence; dependent measures assessed frequency of marijuana use and other illicit drug use during early adulthood for initiators of the respective drug categories. The authors found that intensity of marijuana use was directly associated with the personality, parental, and self-drug-use domains and indirectly associated with the peer domain. Intensity of other illicit drug use was directly associated with personality and self-drug use. Analyses also revealed that some parent-adolescent relations factors buffered the effects of risk factors for both marijuana and other illicit drug-use intensity, whereas others enhanced the effects of protective factors against other illicit drug-use intensity. The results indicate that there are both commonalities and differences in precursors of marijuana and other illicit drug-use intensity among initiators of these drugs during early adulthood.