Differences in onset and persistence of substance abuse and dependence among whites, blacks, and Hispanics.

Objective: This article describes patterns of onset, persistence, and cessation of substance abuse among whites, blacks, and Hispanics that are masked in cross-sectional prevalence data.

Methods: The authors analyzed longitudinal data from a sample of 1,004 white, black, and Hispanic respondents from Chicago to investigate processes of onset, persistence, and cessation of substance abuse and dependence for two age cohorts, 15 and 18 at baseline and 17 and 20 at follow-up.

Results: The data show few racial or ethnic differences in the prevalence of alcohol and marijuana abuse and dependence at age 15. Rates of onset of alcohol abuse and dependence among whites between ages 15 and 17 were significantly higher than for blacks and Hispanics, and the rates of onset of marijuana abuse and dependence among blacks between ages 18 and 20 were significantly higher than for whites and Hispanics of the same age group. There were few significant differences among the three groups in the persistence rates of abuse and dependence.

Conclusion: By age 20 the rates of marijuana abuse and dependence are significantly higher among blacks than among whites and Hispanics.