Cannabis is a widely used drug of abuse in adolescents. With legalization of marijuana, adolescent cannabis use may increase substantially. Clinicians are often faced with a depressed, anxious, or suicidal adolescent who uses cannabis to self-medicate symptoms and is unwilling to stop using cannabis. Several recent studies provide further evidence of the adverse mental health consequences of cannabis use in adolescents.
Depression, anxiety, suicidality
A systematic review and meta-analysis examined the risk of adolescent cannabis use in the development of major depression, anxiety, and suicidal behavior.1 The analysis included longitudinal and prospective studies of cannabis use in adolescents aged younger than 18 years who were then assessed in young adulthood (aged 18-32 years). Eleven studies for a total sample of 23,317 adolescent cannabis users were included in the analysis.
The risk of depression (odds ratio [OR] = 1.4), suicidal ideation (OR = 1.5), and suicide attempt (OR = 3.5) in young adulthood was significantly higher in adolescent cannabis users than in nonusers; a significantly increased risk was not found for the development of anxiety disorders (odds ratio = 1.2). It is important to note that the increased risk of depression and suicidal behavior in young adulthood was present even in the absence of a premorbid psychiatric condition. Based on this study, the researchers concluded that the estimated population attributable risk of depression from cannabis use is 7.2% in adolescents; approximately 413,326 cases of adolescent depression are potentially attributable to cannabis use.
Age, cannabis use frequency, and mental health problems
The effects of age on cannabis use frequency and cannabis use disorder on psychotic, depression, and anxiety symptoms in adolescents and adults were evaluated by Leadbeater and colleagues.2 A randomly recruited sample of 662 adolescents aged 12 to 18 years was assessed over a 10-year period.
More frequent cannabis use was significantly associated with more depressive symptoms from ages 16 to 19 and after age 25. Furthermore, cannabis use was significantly associated with psychotic symptoms after age 22. There was no association between frequency of cannabis use and anxiety symptoms in the study sample. With regard to cannabis use disorder, there was an association with higher depressive symptoms at ages 19 to 20 and after age 25; psychotic symptoms after age 23 were associated with adolescent cannabis use disorder. Cannabis use disorder was also associated with higher anxiety symptoms at ages 26 to 27.
Dr Wagner is Professor and Chair, Department of Psychiatry and Behavioral Sciences, University of Texas Medical Branch, Galveston, TX. She is President of the American Academy of Child and Adolescent Psychiatry.
1. Gobbi G, Atkin T, Zytynski T, et al. Associations of cannabis use in adolescence and risk of depression, anxiety, and suicidality in young adulthood: a systematic review and meta-analysis. JAMA Psychiatry. 2019;76:426-434.
2. Leadbeater BJ, Ames ME, Linden-Carnichael AN. Age-varying effects of cannabis use frequency and disorder on symptoms of psychosis, depression and anxiety in adolescents and adults. Addiction. 2018;114:278-293.
3. Morin JG, Afzali MH, Bourque J, et al. A population-based analysis of the relationship between substance use and adolescent cognitive development. Am J Psychiatry. 2019;176:98-106.
4. Blair RJ, White SF, Tyler PM, et al. Threat responsiveness as a function of cannabis and alcohol use disorder severity. J Child Adolesc Psychopharmacol. June 2019; Epub ahead of print.
5. Wilson J, Freeman TP, Mackie CJ. Effects of increasing cannabis potency on adolescent health. Lancet Child Adolesc Health. 2019;3:121-128.