A synthesis of the relationship of marijuana use with delinquent and problem behaviors

Marijuana use has been identified in both the popular and scientific litera tures as a primary factor leading to later delinquent and problem behaviors . In this article we use meta-analytic techniques to summarize the findings from longitudinal research on this relationship and we delineate what thes e studies tell us about the magnitude of their longitudinal and cross-secti onal relationships. Using multiple search strategies we identified 63 repor ts of 30 independent longitudinal studies from which we coded 511 effect-si zes. The cross-sectional findings measured early in adolescence are the str ongest; these findings generally attenuate with age. For longitudinal relat ionships, stronger mean correlations are observed when delinquent and probl em behaviors are measured first. The general strength and pattern of findin gs suggest that the nature of the relationship is likely to be one of co-mo rbidity and not cause and effect.