A systematic review of 78 studies found cannabis use associated with increased depressive and manic symptoms, higher likelihood of developing mood disorders, and worse treatment outcomes for both major depression and bipolar disorder.
Psychiatrists, primary care providers, and people with mood disorders who use cannabis
Cannabis linked to worse outcomes in both depression and bipolar disorder
What the researchers found
Cannabis use was associated with increased depressive and manic symptoms in the general population, elevated likelihood of developing both major depressive disorder (MDD) and bipolar disorder (BD), and unfavorable prognosis in people already diagnosed with either condition. The relationship held across both cross-sectional and longitudinal study designs.
Why it matters
Cannabis is often used recreationally by people with mood disorders, and some advocate for its use as a mood treatment. This comprehensive review challenges that narrative, finding consistent associations between cannabis use and worse mood disorder outcomes across a large body of evidence.
The numbers in context
3,262 studies screened, 78 met criteria. Associations found with: increased depressive symptoms, increased manic symptoms, elevated risk of developing MDD, elevated risk of developing BD, unfavorable prognosis in both MDD and BD.
How the study worked
Systematic review following PRISMA guidelines. Searched EMBASE, PsycINFO, PubMed, and MEDLINE from inception through November 2023. Of 3,262 studies identified, 78 met inclusion criteria. Both cross-sectional and longitudinal designs were included.
What this study cannot tell us
The review is limited by the observational nature of most included studies. Confounders including concurrent substance use, genetics, and socioeconomic factors may explain some associations. Cannot determine whether cannabis causes mood problems or whether people with mood vulnerability are drawn to cannabis.
How to read the evidence
Large systematic review with 78 studies and registered protocol, though limited by observational evidence.
When this study was published
2024 systematic review
The bigger picture
The finding that cannabis is associated with worse outcomes across both poles of mood disorders (depression and mania) and at both stages (development and prognosis) paints a consistent picture that challenges the self-medication hypothesis for mood conditions.
Questions still open
- Would specific cannabis constituents (CBD vs THC) have different effects on mood? Does the association hold at low-frequency use, or is it primarily a heavy-use phenomenon? Could cannabis withdrawal rather than cannabis use itself explain mood worsening?
Common questions
Does cannabis help or hurt depression?
Is cannabis bad for bipolar disorder?
Read the original research
Cannabis use and mood disorders: a systematic review.
Frontiers in public health, 12, 1346207
Citation
Sorkhou, Maryam; Dent, Eliza L; George, Tony P. (2024). Cannabis use and mood disorders: a systematic review.. Frontiers in public health, 12, 1346207. https://doi.org/10.3389/fpubh.2024.1346207
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