The Formation of a Socioeconomic Disparity. A Case Study of Cocaine and Marijuana Use in the 1990s

Background: Around the year 1990, the reputation of cocaine use changed from glamorous to undesirable, and at the same time, a socioeconomic disparity in cocaine use emerged. This study examined (1) whether the socioeconomic disparity was created by differential incidence, differential cessation, or both, (2) whether a socioeconomic disparity also developed in marijuana use, and (3) whether disparities formed across race, Hispanic ethnicity, and/or gender. Methods: The analyses center on 6544 respondents aged 14-21 in 1979 in the National Longitudinal Survey of 1979 that provided information on past-year use of powder cocaine and marijuana use before and after 1990-specifically, in 1984, 1988, 1992, 1994, and 1998. Results: Both differential incidence and differential cessation across education contributed to the formation of the socioeconomic disparity in cocaine use, although differential cessation played a more influential role in this cohort. A socioeconomic disparity in marijuana use also came about around the same time. No emerging disparities by race, Hispanic ethnicity, or gender were observed. Conclusions: This case study suggests that the redefinition of a health behavior as unhealthy will result in a socioeconomic disparity in the behavior across socioeconomic strata as a result of both differential incidence and cessation, but disparities will not necessarily form by race, ethnicity, or gender.