Trends in the disapproval and use of marijuana among adolescents and young adults in the United States: 2002-2013.

Background: Despite policy changes related to the use and distribution of marijuana in cities and states across the country, few studies have examined changes in disapproval and use of marijuana among American youth.

Objectives: To examine trends in disapproval and use of marijuana among adolescents and young adults in the United States.

Method: We employed nationally representative data spanning the period of 2002-2013. Analyses were based on self-reported measurements from 105,903 younger adolescents (aged 12-14); 110,949 older adolescents (aged 15-17); and 221,976 young adults (aged 18-25).

Results: Between 2002 and 2013 the proportion of adolescents aged 12-14 reporting "strong disapproval" of marijuana use initiation increased significantly from 74.4-78.9%. Concurrently, a significant decrease in past 12-month marijuana use (OR = 0.98, 95% CI = 0.97-0.99) was observed among younger adolescents. No significant trend was observed for marijuana use disapproval among adolescents aged 15-17 between 2002 and 2013. Yet a significant (OR = 0.99, 95% CI = 0.98-0.99) decrease in the past 12-month marijuana use was observed (2002 = 26.2%, 2013 = 21.9%) among this group. Among young adults (aged 18-25), a substantial decrease - from 40.5% in 2002 to 22.6% in 2013 - was observed in the proportion reporting "strong disapproval" of marijuana use initiation; however, increases in the past 12-month use were relatively small among young adults (Δ = 2.21) but statistically significant (OR = 1.02, 95% = 1.01-1.02).

Conclusions: Changes are underway in the perception and use of marijuana among American youth. However, changes differ in important ways among youth from distinct developmental subgroups.