People who have used cannabis before the age of 18 are more likely to experience depression and suicidal thoughts or attempts as young adults compared with those who have not used cannabis in their teens, research has shown. The authors behind the study,* published in JAMA Psychiatry, said that although individual-level risk remains moderate to low, the high prevalence of adolescents consuming cannabis generates a large number of young people who could develop depression and suicidality attributable to the drug – so we urgently need better programmes to educate adolescents about the risks of cannabis use and give them the skills to resist peer pressure on drug consumption.
The research team noted that although cannabis is the most commonly used drug of abuse by adolescents in the world, and the impact of adolescent cannabis use on the development of psychosis has been investigated in depth, little is known about the impact of cannabis use on mood and suicidality in young adulthood. To address this gap, they conducted a systematic review and meta-analysis of 11 longitudinal and prospective studies that had assessed cannabis use in adolescents younger than 18 years and then ascertained development of depression in young adulthood (age 18 to 32 years); these included a total of 23,317 individuals.
Their analysis revealed a statistically significant association between teen cannabis use and depression, suicidal ideation and suicidal attempt. The odds ratio (OR) of developing depression for cannabis users in young adulthood compared with non-users was 1.37; the pooled OR for suicidal ideation was 1.50; and for suicidal attempt it was 3.46. The pooled OR for anxiety was not statistically significant, at 1.18.
The study authors said their analysis was limited in that not all included studies allowed for potential confounding factors, the definitions of depression varied, and the exact quantity of cannabis used was unknown; furthermore, the potency of cannabis has generally increased since 1980, and potency also varies across geographic location.
They commented: “Although individual-level risk remains moderate to low and results from this study should be confirmed in future adequately powered prospective studies, the high prevalence of adolescents consuming cannabis generates a large number of young people who could develop depression and suicidality attributable to cannabis.”
They added: “Given the likelihood of a window of risk during adolescence when the deleterious effects of cannabis are most pronounced, the findings in this meta-analysis suggest that cannabis is a serious public health concern and there is an urgent need to implement better drug use prevention programmes targeting the use of cannabis among adolescents and interventions aimed at educating adolescents to develop the skills to resist peer pressure on drug consumption.”
* Gobbi G, Atkin T, Zytynski T, et al. Association of cannabis use in adolescence and risk of depression, anxiety, and suicidality in young adulthood: a systematic review and meta-analysis. JAMA Psychiatry. Published online February 13, 2019. doi:10.1001/jamapsychiatry.2018.4500.