title: The formation of a socioeconomic disparity: a case study of cocaine and marijuana use in the 1990s.
abstract: 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.
authors.affiliation: Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, USA. Richard.Miech@cudenver.edu
authors.forename: Richard
authors.initials: R
authors.lastname: Miech
authors.forename: Howard
authors.initials: H
authors.lastname: Chilcoat
mesh_terms: D000293:Adolescent; D000328:Adult; D019970:Cocaine-Related Disorders / Q000453:epidemiology*; D005260:Female; D015438:Health Behavior; D006306:Health Surveys; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D002189:Marijuana Abuse / Q000453:epidemiology*; D044469:Racial Groups; D012959:Socioeconomic Factors; D014481:United States / Q000453:epidemiology