People with Psychosis Report More Intense Reactions to Cannabis
First-episode psychosis patients reported more frequent psychotic-like experiences during cannabis intoxication than controls, and this sensitivity increased with heavier use, suggesting a specific vulnerability.
Quick Facts
What This Study Found
In the EU-GEI study across 15 sites and 6 countries, FEP patients (n=655) showed a steeper increase in psychotic-like intoxication experiences at higher cannabis use levels compared to controls (n=654), while euphoric experiences did not differ between groups.
Key Numbers
655 FEP patients; 654 controls; 15 sites across 6 countries; significant interaction for caseness x frequency of use for psychotic-like experiences (p<0.001) but not euphoric experiences (p>0.5).
How They Did This
Multi-site case-control analysis from the EU-GEI study (2010-2015) using multiple regression to model predictors of cannabis-induced psychotic-like and euphoric experiences across 15 sites in 6 countries.
Why This Research Matters
The finding that psychosis patients have a specific vulnerability to cannabis-induced psychotic-like experiences, but not euphoric ones, suggests a biological mechanism rather than simply heavier use patterns.
The Bigger Picture
These findings suggest that people who develop psychosis may have a pre-existing or illness-related sensitivity to the psychotomimetic effects of cannabis that is dose-dependent and distinct from the drug's rewarding effects.
What This Study Doesn't Tell Us
Cross-sectional design cannot determine whether sensitivity preceded psychosis onset; retrospective self-report of intoxication experiences; potential recall bias in patient group.
Questions This Raises
- ?Could measuring psychotic-like cannabis experiences serve as an early warning sign for psychosis risk?
- ?Is this heightened sensitivity present before the first psychotic episode?
Trust & Context
- Key Stat:
- FEP patients showed dose-dependent increases in psychotic-like cannabis experiences that controls did not
- Evidence Grade:
- Large multi-national case-control study with robust statistical methods, though limited by cross-sectional design and retrospective self-report.
- Study Age:
- Data from EU-GEI study collected 2010-2015.
- Original Title:
- Association of extent of cannabis use and psychotic like intoxication experiences in a multi-national sample of first episode psychosis patients and controls.
- Published In:
- Psychological medicine, 51(12), 2074-2082 (2021)
- Authors:
- Sami, Musa, Quattrone, Diego(18), Ferraro, Laura(13), Tripoli, Giada, Cascia, Erika La, Gayer-Anderson, Charlotte, Selten, Jean-Paul, Arango, Celso, Bernardo, Miguel, Tarricone, Ilaria, Tortelli, Andrea, Gatto, Giusy, Del Peschio, Simona, Del-Ben, Cristina Marta, Rutten, Bart P, Jones, Peter B, van Os, Jim, de Haan, Lieuwe, Morgan, Craig, Lewis, Cathryn, Bhattacharyya, Sagnik, Freeman, Tom P, Lynskey, Michael, Murray, Robin M, Forti, Marta Di
- Database ID:
- RTHC-03490
Evidence Hierarchy
Compares people with a condition to similar people without it.
What do these levels mean? →Frequently Asked Questions
Do people with psychosis get more paranoid from cannabis than others?
In this study, first-episode psychosis patients reported more frequent psychotic-like experiences during cannabis intoxication, and this gap widened with heavier use. However, euphoric experiences were similar between groups.
Does heavier cannabis use affect people with psychosis differently?
Yes. While both groups reported more psychotic-like experiences with heavier use, the increase was significantly steeper for psychosis patients, suggesting a specific dose-dependent vulnerability.
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Cite This Study
https://rethinkthc.com/research/RTHC-03490APA
Sami, Musa; Quattrone, Diego; Ferraro, Laura; Tripoli, Giada; Cascia, Erika La; Gayer-Anderson, Charlotte; Selten, Jean-Paul; Arango, Celso; Bernardo, Miguel; Tarricone, Ilaria; Tortelli, Andrea; Gatto, Giusy; Del Peschio, Simona; Del-Ben, Cristina Marta; Rutten, Bart P; Jones, Peter B; van Os, Jim; de Haan, Lieuwe; Morgan, Craig; Lewis, Cathryn; Bhattacharyya, Sagnik; Freeman, Tom P; Lynskey, Michael; Murray, Robin M; Forti, Marta Di. (2021). Association of extent of cannabis use and psychotic like intoxication experiences in a multi-national sample of first episode psychosis patients and controls.. Psychological medicine, 51(12), 2074-2082. https://doi.org/10.1017/S0033291720000847
MLA
Sami, Musa, et al. "Association of extent of cannabis use and psychotic like intoxication experiences in a multi-national sample of first episode psychosis patients and controls.." Psychological medicine, 2021. https://doi.org/10.1017/S0033291720000847
RethinkTHC
RethinkTHC Research Database. "Association of extent of cannabis use and psychotic like int..." RTHC-03490. Retrieved from https://rethinkthc.com/research/sami-2021-association-of-extent-of
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkTHC research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.