title: Marijuana use trajectories during the post-college transition: health outcomes in young adulthood.
abstract: BACKGROUND
  Despite the relatively high prevalence of marijuana use among college students, little information exists regarding health outcomes associated with different use patterns or trajectories.
  
  
  METHODS
  Seven annual personal interviews (years 1-7) were administered to 1253 individuals, beginning in their first year in college. Growth mixture modeling was used to identify trajectories of marijuana, alcohol, and tobacco use frequency during years 1-6. Logistic regression was used to evaluate the relationship between marijuana use trajectories and several year 7 health outcomes, holding constant year 1 health, demographics, and alcohol and tobacco use trajectories.
  
  
  RESULTS
  Six marijuana use trajectories were identified: non-use (71.5% (wt) of students), low-stable (10.0% (wt)), late-increase (4.7% (wt)), early-decline (4.3% (wt)), college-peak (5.4% (wt)), and chronic (4.2% (wt)). The six marijuana trajectory groups were not significantly different on year 1 health-related variables, but differed on all ten year 7 health outcomes tested, including functional impairment due to injury, illness, or emotional problems; general health rating; psychiatric symptoms; health-related quality of life; and service utilization for physical and mental health problems. Non-users fared significantly better than most of the marijuana-using trajectory groups on every outcome tested. Chronic and late-increase users had the worst health outcomes.
  
  
  CONCLUSIONS
  Marijuana use patterns change considerably during college and the post-college period. Marijuana-using students appear to be at risk for adverse health outcomes, especially if they increase or sustain a frequent pattern of use.
authors.affiliation: Center on Young Adult Health and Development, University of Maryland School of Public Health, Department of Family Science, 1142 School of Public Health Building, College Park, MD 20742, USA.
authors.forename: Kimberly M
authors.initials: KM
authors.lastname: Caldeira
authors.forename: Kevin E
authors.initials: KE
authors.lastname: O'Grady
authors.forename: Kathryn B
authors.initials: KB
authors.lastname: Vincent
authors.forename: Amelia M
authors.initials: AM
authors.lastname: Arria
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000428:Alcohol Drinking / Q000453:epidemiology; D001499:Bayes Theorem; D003710:Demography; D005260:Female; D006296:Health Services / Q000706:statistics & numerical data; D006304:Health Status; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D002189:Marijuana Abuse / Q000453:epidemiology*; D001523:Mental Disorders / Q000150:complications / Q000453:epidemiology; D008873:Mid-Atlantic Region / Q000453:epidemiology; D011569:Psychiatric Status Rating Scales; D011788:Quality of Life; D012044:Regression Analysis; D012959:Socioeconomic Factors; D014029:Tobacco Use Disorder / Q000453:epidemiology; D014495:Universities; D055815:Young Adult