Frequent cannabis use during adolescence significantly increases the risk of depression and anxiety disorders in young adulthood, especially with daily use in girls.
Summary
Prospective cohort study (n=1601, age 14–20 years): Daily cannabis use in young women associated with OR=5,6 (95%-KI 2,6–12,0) for anxiety disorder and depression in young adulthood (combined outcome). Weekly use: OR≈1,9 (95%-KI 1,1–3,3). Prior anxiety did not predict later cannabis use (no reverse causation).
P
PopulationSecondary school students from 44 schools in Victoria, Australia, n=1601, age 14–15 years at baseline, followed for over 7 years to age ~20
I
InterventionFrequent cannabis use (weekly or daily) during adolescence
C
ControlInfrequent or no cannabis use
O
OutcomeDaily cannabis use in young women associated with >5-fold increase in odds of depression/anxiety (OR 5,6; 95%-KI 2,6–12); weekly use with ~2-fold risk (OR 1,9; 95%-KI 1,1–3,3) after adjustment
Confidence in the evidence
Very lowLowModerateHigh
Low
The second of four GRADE levels, the effect estimate is of limited reliability.
<h4>Objective</h4>To determine whether cannabis use in adolescence predisposes to higher rates of depression and anxiety in young adulthood.<h4>Design</h4>Seven wave cohort study over six years.<h4>Setting</h4>44 schools in the Australian state of Victoria.<h4>Participants</h4>A statewide secondary school sample of 1601 students aged 14-15 followed for seven years.<h4>Main outcome measure</h4>Interview measure of depression and anxiety (revised clinical interview schedule) at wave 7.<h4>Results</h4>Some 60% of participants had used cannabis by the age of 20; 7% were daily users at that point. Daily use in young women was associated with an over fivefold increase in the odds of reporting a state of depression and anxiety after adjustment for intercurrent use of other substances (odds ratio 5.6, 95% confidence interval 2.6 to 12). Weekly or more frequent cannabis use in teenagers predicted an approximately twofold increase in risk for later depression and anxiety (1.9, 1.1 to 3.3) after adjustment for potential baseline confounders. In contrast, depression and anxiety in teenagers predicted neither later weekly nor daily cannabis use.<h4>Conclusions</h4>Frequent cannabis use in teenage girls predicts later depression and anxiety, with daily users carrying the highest risk. Given recent increasing levels of cannabis use, measures to reduce frequent and heavy recreational use seem warranted.