The contribution of cannabis use to variation in the incidence of psychotic disorder across Europe (EU-GEI): a…
Given my family history and the potency of what is sold now, what is my personal risk of a psychotic episode if I keep using cannabis daily?
Reasonable evidence with real limitations. how we score evidence
Caveat on this rating: This is a case-control design, so it establishes association and a dose-response pattern rather than proving causation; reverse causation (early psychotic symptoms driving heavier use) and residual confounding cannot be fully excluded, which is why the authors flag the population-attributable fractions as conditional on causality.
Botanical cannabis has never been FDA-approved for any psychiatric indication.
Comparing 901 people presenting with first-episode psychosis against 1,237 population controls across 11 European and Brazilian sites, daily cannabis use was associated with about three times the odds of psychotic disorder (adjusted OR 3.2, 95% CI 2.2-4.1) and daily use of high-potency cannabis (THC 10% or more) with nearly five times the odds (OR 4.8, 2.5-6.3). Assuming causality, removing high-potency cannabis would prevent an estimated 12.2% of first-episode psychosis across all sites, 30.3% in London, and 50.3% in Amsterdam.
Worth asking
Given my family history and the potency of what is sold now, what is my personal risk of a psychotic episode if I keep using cannabis daily?
Source
The contribution of cannabis use to variation in the incidence of psychotic disorder across Europe (EU-GEI): a multicentre case-control study. — Di Forti M, Quattrone D, Freeman TP, et al. (2019)
Top-tier peer-reviewed journal
Read the source: https://doi.org/10.1016/S2215-0366(19)30048-3
DOI: 10.1016/S2215-0366(19)30048-3
How this was scored
- Study design
- Case-control study
- Funding
- Independently funded
- Published in
- Top-tier peer-reviewed journal
- Sample size
- 2,138
- Preregistered
- No
- Conflicts disclosed
- No
- Independent of proponent
- Yes
- Retracted
- No
Read the full scoring rubric, including what it can't tell you.
Published August 19, 2026.
Questions
How strong is the evidence behind this?
Resolv rates this source "moderate evidence". Reasonable evidence with real limitations. It scores 68 out of 100 on our published rubric. One caveat travels with that badge: This is a case-control design, so it establishes association and a dose-response pattern rather than proving causation; reverse causation (early psychotic symptoms driving heavier use) and residual confounding cannot be fully excluded, which is why the authors flag the population-attributable fractions as conditional on causality. 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?
The contribution of cannabis use to variation in the incidence of psychotic disorder across Europe (EU-GEI): a multicentre case-control study. — Di Forti M, Quattrone D, Freeman TP, et al. (2019). Published in: Top-tier peer-reviewed journal. DOI: 10.1016/S2215-0366(19)30048-3. 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: Case-control study. Funding: Independently funded. The researchers were independent of whoever benefits from the result. 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.