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Cannabis Impact on Depression, Anxiety, and Suicide in Adolescents

Better drug prevention and education programs are needed, urge researchers

A PPM Brief

Researchers recently investigated cannabis use during adolescence (18 years and younger) through systematically reviewing and analyzing longitudinal prospective cohort studies and evaluating the risk of depression, anxiety, and suicidality during young adulthood (18 to 32 years; only longitudinal prospective cohort studies controlling for baseline depression were included in the study). The studies assessed cannabis use and depression at different points from adolescence to young adulthood and reported the corresponding odds ratio (OR). In the studies selected, depression was diagnosed according to the third or fourth editions of the Diagnostic and Statistical Manual of Mental Disorders or by using scales with predetermined cutoff points.

Screening 3,142 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 pooled OR for depression during young adulthood among cannabis users compared with nonusers was 1.37 (95% CI, 1.16-1.62; I2 = 0%). Cannabis use during adolescence was associated with an OR of 1.18 for developing anxiety in young adulthood (95% CI, 0.84-1.67; I2 = 42.0%). Results that had measured the association of cannabis use during adolescence with subsequent suicidal ideation within adolescence and in young adulthood were pooled with a resultant OR of 1.50 (95% CI, 1.11-2.03; I2: 0%). For the number of suicide attempt outcomes within adolescence or during young adulthood, the results were pooled with a resultant OR of 3.46 (95% CI, 1.53-7.84; I2 = 61.3%).

(Source: 123RF)

Noting the moderately increased risk of depression in this population, the researchers noted that while “the causes of major depressive disorder are multifactorial and complex,” exposure to cannabis could be one contributing factor to depression in young adulthood. “This study also is consistent with the greater part of research on brain imaging literature demonstrating the negative influence of cannabis in brain plasticity,” the researchers continued. “The brain indeed remains in a state of active, experience-guided development from the prenatal period through childhood and adolescence until the age of approximately 21 years. During this period, it is intrinsically more vulnerable to the adverse long-term effects of environmental insults, such as exposure to THC.”

The researchers went on to conclude that “these findings highlight the importance of initiatives aiming to educate teenagers on the risks associated with using cannabis and teach them skills to resist peer pressure.” They noted that given the likelihood of risk during adolescence when effects of cannabis are most pronounced, findings suggest that cannabis is a serious public health concern and there is an urgent need to implement better drug use prevention programs.

Last updated on: July 11, 2019
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