Study: Adolescent Cannabis Use Not Independently Predictive of Depression, Suicidal Ideation

Quebec, Canada: Cannabis use by adolescents is not independently predictive of either depression or suicidal ideation, according to longitudinal data published in the Journal of Affective Disorders.

A team of Canadian investigators examined the relationship between cannabis use at age 15 and the likelihood of depressive symptoms and suicidal ideation at age 20 in a cohort of over 1,600 adolescents.

Researchers reported that cannabis use was not independently associated with a greater risk of suicidal thoughts at young adulthood after investigators controlled for subjects’ use of alcohol, tobacco, and other substances. In addition, researchers reported that adolescents who suffered from depression were more likely to use cannabis later in life, not vice-versa.

Authors concluded: “This population-based study is the first, to our knowledge, to examine the temporal relation between cannabis use, depression and suicidal ideation simultaneously over five years during adolescence. Depression (but not suicidal ideation) predicted weekly cannabis use throughout adolescence. Weekly cannabis use predicted suicidal ideation (but not depression), but this association was no longer significant after taking into account other substance use including alcohol, tobacco and other drugs consumption. … These findings highlight the importance of targeting depressive symptoms during this sensitive developmental period in an attempt to offset the potential increased use of cannabis over time.”

In June, NIH researchers published data in the Journal of the American Medical Association highlighting an association between frequent cannabis use and elevated levels of suicidal ideation in young adults. However, authors of the study neither controlled for the use of other drugs, nor did they assess whether the relationship was bidirectional.

Full text of the study, “Cannabis use, depression and suicidal ideation in adolescence: Direction of associations in a population-based cohort,” appears in the Journal of Affective Disorders.