Cannabis and mental health in adolescents: changes in associations over 15 years

Recent changes in the cannabis market, including decreased adolescence usage, increased Δ9-tetrahydrocannabinol levels and rising mental disorders over the last decade raises questions about the changing profile of cannabis consumers.

This study explores the trends of associations between regular cannabis use and mental health in five waves of a national representative survey of 17-year-old French adolescents, including more than 150,000 participants. Multivariable models, adjusted for gender and socioeconomic variables, were used.

Cannabis use and mental health indicators showed some variations over time, with increasing divergence between 2017 and 2022. Regular use of cannabis decreased from 7.4% in 2008 to 3.8% in 2022 (p < 0.001). In contrast, suicidal ideation in the past year increased from 16% in 2008 to 18% in 2022 (p = 0.009), although it followed a U-shaped trend. The association between regular cannabis use and suicidal ideation in the past year increased from 1.44 (CI: 1.29-1.61) in 2008 to 2.52 (CI: 2.05-3.10) in 2022. Similarly, the association between cannabis use and antidepressant use in the past year increased from 2.57 (CI: 2.18-3.03) in 2008 to 4.47 (CI: 3.35-5.97) in 2022.

These results suggest that cannabis users are now more prone to mental health disorders compared to 15 years ago. Several mechanisms might explain these findings, including the self-selection of a population with both vulnerabilities, changes in the effects of cannabis, or the use of cannabis as a self-medication strategy.