Meta-analysis of the Association Between the Level of Cannabis Use and Risk of Psychosis.
If risk rises with how much I use, is cutting down meaningfully protective, or does the evidence only support stopping?
Reasonable evidence with real limitations. how we score evidence
Caveat on this rating: Built entirely from observational studies with heterogeneous definitions of "heavy" use; the pooled odds ratio was generated by simulating individual data points from summary statistics, a method that depends on assumptions about the underlying distributions.
Botanical cannabis has never been FDA-approved for any psychiatric indication.
Across 10 studies and 66,816 people, the heaviest cannabis users had almost four times the odds of schizophrenia and related psychotic outcomes compared with non-users (OR 3.90, 95% CI 2.84-5.34), and every included study showed higher risk at higher levels of use. The consistent dose-response gradient is what makes this association hard to dismiss as confounding alone, though the authors stop short of claiming proof of causation.
Worth asking
If risk rises with how much I use, is cutting down meaningfully protective, or does the evidence only support stopping?
Source
Meta-analysis of the Association Between the Level of Cannabis Use and Risk of Psychosis. — Marconi A, Di Forti M, Lewis CM, Murray RM, Vassos E. (2016)
Reputable peer-reviewed journal
Read the source: https://doi.org/10.1093/schbul/sbw003
DOI: 10.1093/schbul/sbw003
How this was scored
- Study design
- Systematic review of observational studies
- Funding
- Funding not disclosed
- Published in
- Reputable peer-reviewed journal
- Sample size
- 66,816
- Preregistered
- No
- Conflicts disclosed
- No
- Independent of proponent
- not recorded
- Retracted
- No
Read the full scoring rubric, including what it can't tell you.
Published August 19, 2026.
Where we put this study in context
Questions
How strong is the evidence behind this?
Resolv rates this source "moderate evidence". Reasonable evidence with real limitations. It scores 59 out of 100 on our published rubric. One caveat travels with that badge: Built entirely from observational studies with heterogeneous definitions of "heavy" use; the pooled odds ratio was generated by simulating individual data points from summary statistics, a method that depends on assumptions about the underlying distributions. The score is calculated from recorded facts about the source — study design, funding, publication venue, sample size, preregistration — not typed in by an editor.
What is the source for this?
Meta-analysis of the Association Between the Level of Cannabis Use and Risk of Psychosis. — Marconi A, Di Forti M, Lewis CM, Murray RM, Vassos E. (2016). Published in: Reputable peer-reviewed journal. DOI: 10.1093/schbul/sbw003. The full source is linked on this page so you can read it yourself.
Who paid for this research, and does that matter?
Study design: Systematic review of observational studies. Funding: Funding not disclosed. Independence from the proponent is not recorded. Industry sponsorship is one of the most reliably measured biases in medicine, which is why funding carries real weight in the score rather than sitting in a footnote.
Is cannabis-thc, marijuana, weed, thc, delta-9-tetrahydrocannabinol, medical cannabis, dronabinol, nabiximols FDA approved for this use?
No. Its current status is: Not FDA-evaluated for this use. Botanical cannabis has never been FDA-approved for any psychiatric indication.
Is this medical advice?
This is information to bring to your prescriber, not medical advice and not a reason to change anything on your own. Nothing here is an instruction to stop or reduce a medication. If you are in crisis, call or text 988.
This is information to bring to your prescriber, not medical advice and not a reason to change anything on your own. Nothing here is an instruction to stop or reduce a medication. If you are in crisis, call or text 988.