Associations of adolescent cannabis use with academic performance and mental health: A longitudinal study of upper middle class youth

Drug Alcohol Depend. 2015 Nov 1;156:207-212. doi: 10.1016/j.drugalcdep.2015.09.010. Epub 2015 Sep 21.

Abstract

Background: There is a hypothesis that low socioeconomic status (SES) may explain the link between cannabis use and poorer academic performance and mental health. A key question, therefore, is whether adolescent cannabis use is associated with poorer academic performance and mental health in high SES communities where there is reduced potential for confounding.

Methods: Youth (n=254) from an upper middle class community were followed prospectively through the four years of high school (from age 14/15 to age 17/18). Past-year frequency of cannabis use was assessed annually. Official school records of academic performance and self-reported mental health symptoms (externalizing and internalizing symptoms) were assessed in grades 9 and 12.

Results: Persistent cannabis use across the four years of high school was associated with lower grade-point average (β=-0.18, p=.006), lower Scholastic Aptitude Test (SAT) score (β=-0.13, p=.038), and greater externalizing symptoms (β=0.29, p<.001) in 12th grade, but not with greater internalizing symptoms (β=0.04, p=.53). Moreover, persistent cannabis use was associated with lower grade-point average (β=-0.13, p=.014) and greater externalizing symptoms (β=0.24, p=.002) in 12th grade, even after controlling for 9th grade levels of these outcomes. Similar associations were observed for persistent alcohol and tobacco use. Effects for persistent cannabis use became non-significant after controlling for persistent alcohol and tobacco use, reflecting the difficulties of disentangling effects of cannabis from effects of alcohol and tobacco.

Conclusions: Low SES cannot fully explain associations between cannabis use and poorer academic performance and mental health.

Keywords: Adolescent; Cannabis; Grade-point average; Longitudinal; Mental health; SES.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Adolescent
  • Alcohol Drinking / psychology
  • Aptitude Tests
  • Educational Status*
  • Female
  • Humans
  • Longitudinal Studies
  • Male
  • Marijuana Smoking / epidemiology*
  • Marijuana Smoking / psychology*
  • Mental Health
  • Prospective Studies
  • Sex Factors
  • Social Class*
  • Tobacco Use / psychology