Clinical Question

Are adolescents with a history of cannabis use more likely to develop increased suicidality in adulthood?

Evidence-Based Answer

Adolescents with a history of cannabis use have at least a 50% increase in the odds of developing suicidality in adulthood. (Strength of Recommendation: B, large meta-analysis of cohort studies consistent with an additional cohort and cross-sectional twin study.)

Evidence Summary

A 2019 systematic review and meta-analysis (11 prospective cohort studies; n = 23,317) assessed the association between adolescent cannabis use and the risk of developing depression, anxiety, and suicidality in young adulthood.¹ Included studies enrolled patients younger than 18 years and assessed their cannabis use before 18 years of age with self-reported questionnaires that measured frequency of use over the past 6 to 12 months. Patients with any reported use were pooled and compared with nonusers. All studies individually adjusted the odds ratios (ORs) based on several suspected confounding variables, including a history of depression, alcohol use, sex, or tobacco use. The primary outcomes included rates of suicidal ideation and suicide attempts, assessed by questionnaire or standardized interview assessments at least once between 18 and 32 years of age. A history of cannabis use in adolescence was associated with a 50% increase in the odds of suicidal ideation (three studies; n = 8,479; OR = 1.5; 95% CI, 1.1 to 2.0) and more than a threefold increase in the odds of a suicide attempt (three studies; n = 13,687; OR = 3.4; 95% CI, 1.5 to 7.8) in adulthood. Some studies did not account for potential confounders such as tobacco or other drug use and comorbid psychosocial factors. The exact type, quantity, and potency of cannabis consumed among the studied adolescents were not measured or reported.