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Original Investigation
February 13, 2019

Association of Cannabis Use in Adolescence and Risk of Depression, Anxiety, and Suicidality in Young Adulthood: A Systematic Review and Meta-analysis

Author Affiliations
  • 1Neurobiological Psychiatry Unit, Department of Psychiatry, McGill University Health Center, McGill University, Montreal, Quebec, Canada
  • 2Division of Clinical Epidemiology, McGill University Health Centre-Research Institute, Montreal, Quebec, Canada
  • 3Schulich Library of Physical Sciences, Life Sciences, and Engineering, McGill University, Montreal, Quebec, Canada
  • 4Department of Anesthesia, McGill University, Montreal, Quebec, Canada
  • 5Department of Family Medicine, McGill University, Montreal, Quebec, Canada
  • 6Department of Psychology, Rutgers University, Camden, New Jersey
  • 7Department of Psychiatry, University of Oxford, Warneford Hospital, Oxford, United Kingdom
  • 8Oxford Health National Health Service Foundation Trust, Warneford Hospital, Oxford, United Kingdom
  • 9Center for Outcomes Research and Evaluation, Department of Medicine, School of Physical and Occupational Therapy, McGill University Health Center Research Institute, McGill University, Montreal, Quebec, Canada
JAMA Psychiatry. 2019;76(4):426-434. doi:10.1001/jamapsychiatry.2018.4500
Key Points

Question  Is adolescent cannabis consumption associated with risk of depression, anxiety, and suicidality in young adulthood?

Findings  In this systematic review and meta-analysis of 11 studies and 23 317 individuals, adolescent cannabis consumption was associated with increased risk of developing depression and suicidal behavior later in life, even in the absence of a premorbid condition. There was no association with anxiety.

Meaning  Preadolescents and adolescents should avoid using cannabis as use is associated with a significant increased risk of developing depression or suicidality in young adulthood; these findings should inform public health policy and governments to apply preventive strategies to reduce the use of cannabis among youth.

Abstract

Importance  Cannabis is the most commonly used drug of abuse by adolescents in the world. While 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.

Objective  To provide a summary estimate of the extent to which cannabis use during adolescence is associated with the risk of developing subsequent major depression, anxiety, and suicidal behavior.

Data Sources  Medline, Embase, CINAHL, PsycInfo, and Proquest Dissertations and Theses were searched from inception to January 2017.

Study Selection  Longitudinal and prospective studies, assessing cannabis use in adolescents younger than 18 years (at least 1 assessment point) and then ascertaining development of depression in young adulthood (age 18 to 32 years) were selected, and odds ratios (OR) adjusted for the presence of baseline depression and/or anxiety and/or suicidality were extracted.

Data Extraction and Synthesis  Study quality was assessed using the Research Triangle Institute item bank on risk of bias and precision of observational studies. Two reviewers conducted all review stages independently. Selected data were pooled using random-effects meta-analysis.

Main Outcomes and Measures  The studies assessing cannabis use and depression at different points from adolescence to young adulthood and reporting the corresponding OR were included. In the studies selected, depression was diagnosed according to the third or fourth editions of Diagnostic and Statistical Manual of Mental Disorders or by using scales with predetermined cutoff points.

Results  After screening 3142 articles, 269 articles were selected for full-text review, 35 were selected for further review, and 11 studies comprising 23 317 individuals were included in the quantitative analysis. The OR of developing depression for cannabis users in young adulthood compared with nonusers was 1.37 (95% CI, 1.16-1.62; I2 = 0%). The pooled OR for anxiety was not statistically significant: 1.18 (95% CI, 0.84-1.67; I2 = 42%). The pooled OR for suicidal ideation was 1.50 (95% CI, 1.11-2.03; I2 = 0%), and for suicidal attempt was 3.46 (95% CI, 1.53-7.84, I2 = 61.3%).

Conclusions and Relevance  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. This is an important public health problem and concern, which should be properly addressed by health care policy.

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