Marijuana Law, Policy & Reform

Editor: Douglas A. Berman
Moritz College of Law

Wednesday, 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"

Download (24)The title of this post is the title of this notable new article which just today is published online in JAMA Psychiatry.  Here is its front matter:

Key Points


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


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.


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.



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.


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.


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.

Medical community perspectives, Recreational Marijuana Data and Research | Permalink


Although the authors controlled for pre-existing morbidity, I think there may be some confounding factors such as socioeconomics and healthcare access that may affect who gets treated for depression and how early symptoms are diagnosed.

I also wonder if cannabis as a factor in causing depression was already a suspicion of healthcare providers. I think prospective studies examining changes in brain chemistry or physical structure attributable to cannabis could help to assess the authors’ conclusions. Medical testing of marijuana is pretty sparse, and I think it should get more “real” scientific study, as opposed to lots of correlative studies. For now, the conclusion that “the high prevalence of adolescents consuming cannabis generates a large number of young people who could develop depression and suicidality attributable to cannabis” necessitates further research.

Posted by: Anna Grushetsky | Feb 14, 2019 7:36:02 AM

Excellent points, Anna.

Posted by: Doug B | Feb 14, 2019 7:48:57 AM

I think this is a fascinating study and the data is compelling. I think it will be meaningful for the scientists to study further whether some of the strains of cannabis have a more severe impact on adolescent compared to the others because it has been shown that not all cannabis has the same effect in terms of mental health. I would like to cite this study for my paper as well!

Posted by: Dhohyung Kim | Feb 14, 2019 11:54:58 AM

When I read through the study’s key points, I couldn’t help but focus on the term ‘associated.’ Similar to what I think Anna was pointing out, I think there is a large number of factors in a child’s life that can contribute to both cannabis use at an early age, and depression or similar conditions. I don’t have much background in psychology, but I would think a child who is abused or neglected by their parents is more likely to develop depression and, completely unrelated, is also more likely to have access to cannabis at a young age. That is not to say that cannabis doesn’t cause depression or other conditions because of how it operates at the cellular and neurological level, but I think studies like this are very misleading because, in my experience, most people don’t take the time to distinguish between correlation and causation, especially when the study supports their pre-existing views. Until research is conducted studying the actual physiological/biological effects of cannabis at the neurological level, I don’t think we can really say whether it causes depression or other similar conditions, and many organizations who tout the results of these kinds of studies as essentially definitive (on both sides) are ignorant or disingenuous.

Posted by: Andy Meinert | Feb 19, 2019 8:24:31 AM

Great article. it is very informative. I am glad to read your article.

Posted by: kurt | Feb 26, 2019 5:25:28 PM

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