12 year study shows adolescent use of marijuana declining even as decriminalization increases statewide

05/31/2016 - 10:54

Jim Dryden

A survey of more than 216,000 adolescents from all 50 states indicates the number of teens with marijuana-related problems is declining. Similarly, the rates of marijuana use by young people are falling despite the fact more U.S. states are legalizing or decriminalizing marijuana use and the number of adults using the drug has increased.

Researchers at Washington University School of Medicine in St. Louis examined data on drug use collected from young people, ages 12 to 17, over a 12-year span.


Ref: Declining Prevalence of Marijuana Use Disorders Among Adolescents in the United States, 2002 to 2013. Journal of the American Academy of Child & Adolescent Psychiatry (6 April 2016) | DOI: 10.1016/j.jaac.2016.04.002


Little is known about recent trends in marijuana use disorders among adolescents in the United States. We analyzed trends in the past-year prevalence of DSM-IV marijuana use disorders among adolescents, both overall and conditioned on past-year marijuana use. Potential explanatory factors for trends in prevalence were explored.

We assembled data from the adolescent samples of the 2002 to 2013 administrations of the National Survey on Drug Use and Health (N = 216,852; aged 12−17 years). The main outcome measures were odds ratios describing the average annual change in prevalence and conditional prevalence of marijuana use disorders, estimated from models of marijuana use disorder as a function of year. Post hoc analyses incorporated measures of potentially explanatory risk and protective factors into the trend analyses.

A decline in the past-year prevalence of marijuana use disorders was observed (odds ratio = 0.976 per year; 95% CI = 0.968, 0.984; p < .001). This was due to both a net decline in past-year prevalence of use and a decline in the conditional prevalence of marijuana use disorders. The trend in marijuana use disorders was accounted for by a decrease in the rate of conduct problems among adolescents (e.g., fighting, stealing).

Past-year prevalence of marijuana use disorders among US adolescents declined by an estimated 24% over the 2002 to 2013 period. The decline may be related to trends toward lower rates of conduct problems. Identification of factors responsible for the reduction in conduct problems could inform interventions targeting both conduct problems and marijuana use disorders.