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Adolescent cannabis use increases risk for harmful substance use

Cannabis use in adolescence was associated with increased risk for nicotine dependence, harmful alcohol use and illicit drug use at age 21 years, according to recent findings.

“The potential harms of cannabis use during adolescence include altered brain development, cognitive impairment, chronic bronchitis and adverse mental health outcomes,” Michelle Taylor, MSc, BSc, PhD, of University of Bristol, United Kingdom, and colleagues wrote. “Evidence on the role of adolescent cannabis use as a gateway to use of other illicit drugs, and its relationship with tobacco use and alcohol, is inconsistent.”

To determine patterns of cannabis use among teens and associations with problematic substance use later in life, researchers conducted a longitudinal latent class analysis of self-reports from 5,315 adolescents aged 13 to 18 years. Nicotine dependence, harmful alcohol use and recent use of illicit drugs was assessed at age 21 years.

Overall, 80.1% of the cohort was classified as nonusers of cannabis; 14.2% had late-onset occasional use; 2.3% had early-onset occasional use; and 3.4% were considered regular users.

Cannabis use was significantly associated with sex, maternal substance use, child tobacco use, alcohol consumption and conduct problems.

Participants with late-onset occasional cannabis use (OR = 3.5; 95% CI, 0.7-17.9), early-onset occasional use (OR = 12.1; 95% CI, 1-150.3), and regular users (OR = 37.2; 95% CI, 9.5-144.8) were more likely to use nicotine at age 21 years, compared with nonusers.

Harmful alcohol consumption at age 21 years was more common among participants with late-onset occasional cannabis use (OR = 2.6; 95% CI, 1.5-4.3), early-onset occasional use (OR = 5; 95% CI, 2.1-12.1), and regular users (OR = 2.6; 95% CI, 1-7.1), compared with nonusers.

Further, illicit drug use at age 21 years was more common among participants with late-onset occasional cannabis use (OR = 22.7; 95% CI, 11.3-45.7), early-onset occasional use (OR = 15.9; 95% CI, 3.9-64.4), and regular users (OR = 47.9; 95% CI, 47.9-337), compared with nonusers.

“Adolescent substance use also clusters with other risk behaviors which are strongly associated with outcomes in adulthood,” the researchers wrote. “Our study does not support or refute arguments for altering the legal status of cannabis use — especially since two of the outcomes are legal in the U.K. This study and others do, however, lend support to public health strategies and interventions that aim to reduce cannabis exposure in young people.” – by Amanda Oldt

Disclosure: The researchers report no relevant financial disclosures.