Explanations underlying these observations are emerging. While overall rates of alcohol, marijuana, and tobacco use among Blacks are generally lower than among Whites, several large-scale epidemiologic studies show a convergence in use by age, with rates becoming more similar, or ‘crossing-over’ by age (Caetano, 1984; Feigelman & Lee, 1995; Finlay et al., 2012; Kandel et al., 2011; Pampel, 2008; Robins, 1985; Watt, 2008). While studies vary in the age at which this cross-over occurs, generally the late 20s and early to mid 30s are found to be the critical developmental period for cross-over in substance use (Pampel, 2008; Watt, 2008). Therefore, while lower overall prevalence of use among Black compared with White adolescents is driven by patterns in these early life stages, higher use among Blacks compared with Whites in later stages of adulthood may drive the greater burden of substance use consequences among Blacks. Our understanding of the epidemiological patterns of substance use across race/ethnicity over the lifecourse, however, remains inadequate for several reasons.
