Cannabis use during adolescence is associated with an increased risk of developing depression or suicidal behavior in young adulthood, even in teens with no depressive symptoms prior to starting cannabis, according to a systematic review and meta-analysis published online in JAMA Psychiatry.
“When we started this study, we expected depression to be a factor attributable to cannabis consumption, but we were quite surprised about suicide behavior rates,” said researcher Gabriella Gobbi, MD, PhD, of McGill University in Montreal, Quebec, Canada. “Indeed, a significant percentage of suicidal attempts are linked to cannabis.”
The systematic review and meta-analysis spanned 11 studies and 23,317 people. After adjusting for baseline depression, anxiety, and suicidality, the odds ratio of developing depression between ages 18 and 32 with adolescent cannabis use, compared with no cannabis use, was 1.37, researchers reported. The odds ratio for suicidal ideation was 1.50, and for suicide attempt was 3.46. The odds ratio for anxiety was a statistically insignificant 1.18.
“The study suggests the diagnosis of depression in approximately 7% of Canadians and Americans between the ages of 18 and 30 is linked to cannabis, meaning 25,000 young Canadians and 400,000 young Americans suffer from depression because of earlier cannabis consumption,” said researcher Nancy Mayo, PhD, of McGill University.
According to the authors, more than 20% of adolescents in the United States report monthly use of cannabis. In Canada, 15- to 25-year-olds constitute the majority of the population reporting cannabis use.
“It is clear that a lot of young people consuming cannabis are at risk of developing depression and suicidal behavior, so it is very important for authorities to be more proactive in campaigning for prevention,” said Dr. Gobbi. “We hope the findings will spur public health organizations to apply preventative strategies to reduce the use of cannabis among youth.”
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. 2019 February 13;[Epub ahead of print].