The association between cannabis and depression: an updated Systematic Review and Meta-analysis

Area of Science:

• Psychiatry
• Public Health
• Epidemiology

Background:

• Cannabis is a globally prevalent substance with evolving legal statuses.
• Understanding its mental health impacts, especially on depression, remains crucial.
• This study updates previous findings on the cannabis-depression relationship.

Purpose of the Study:

• To conduct a systematic review and meta-analysis on the longitudinal relationship between cannabis use and depression.
• To provide an updated assessment of the evidence, accounting for recent research.

Main Methods:

• Screened longitudinal studies published before March 2023, excluding cross-sectional designs and special populations.
• Included studies controlling for baseline depression to establish temporal association.
• Employed a random effects model with multilevel meta-regression for analysis.

Main Results:

• Analyzed 22 studies, finding a significantly higher risk of depression among cannabis users (OR: 1.29, 95% CI: 1.13-1.46).
• Identified exposure measurement as a key area of bias across studies.
• Found no evidence of publication bias.

Conclusions:

• The findings confirm a robust association between cannabis use and increased depression risk.
• Further research is essential to define heavy use, understand usage patterns, and assess long-term depression risks.
• Evolving cannabis trends necessitate ongoing investigation into its mental health consequences.