Psychosis patients who used cannabis had better social functioning before getting sick
In a multisite study of 948 first-episode psychosis patients and 1,313 controls across 6 countries, cannabis-using patients had better premorbid social functioning than non-using patients, suggesting social ability may facilitate cannabis exposure.
Quick Facts
What This Study Found
Psychosis patients who used cannabis occasionally or daily had better premorbid social adjustment than patients who never used. This difference was specific to patients and not seen in controls. IQ was 3 points higher in occasional users vs. never-users in both groups.
Key Numbers
948 FEP patients, 1,313 controls, 6 countries. IQ was 3 points higher in occasional users vs. never-users (both groups). Daily users had worse academic adjustment than occasional or never-users (both groups).
How They Did This
Multisite case-control study across 6 countries comparing IQ and premorbid adjustment (academic and social) by cannabis use frequency in 948 first-episode psychosis patients and 1,313 population controls.
Why This Research Matters
This challenges the idea that cannabis use alone explains cognitive differences between psychosis patients. Instead, it suggests that patients who were more socially functional before illness were more likely to encounter and use cannabis.
The Bigger Picture
The finding reframes the cannabis-psychosis relationship: rather than cannabis use being purely a risk factor, better premorbid social functioning may have increased the likelihood of cannabis exposure, which then interacted with existing vulnerability.
What This Study Doesn't Tell Us
Cross-sectional assessment of premorbid functioning relies on retrospective reports. The study cannot determine the direction of causation between social functioning, cannabis use, and psychosis onset.
Questions This Raises
- ?Does better social functioning increase cannabis exposure, which then triggers psychosis in vulnerable individuals?
- ?Should prevention strategies focus on socially active youth with psychosis risk factors?
Trust & Context
- Key Stat:
- Cannabis-using psychosis patients had better premorbid social functioning
- Evidence Grade:
- Strong: large multisite case-control study across 6 countries with over 2,200 participants.
- Study Age:
- Published in 2020 in Schizophrenia Bulletin.
- Original Title:
- Premorbid Adjustment and IQ in Patients With First-Episode Psychosis: A Multisite Case-Control Study of Their Relationship With Cannabis Use.
- Published In:
- Schizophrenia bulletin, 46(3), 517-529 (2020)
- Authors:
- Ferraro, Laura(13), La Cascia, Caterina(12), Quattrone, Diego(18), Sideli, Lucia, Matranga, Domenica, Capuccio, Veronica, Tripoli, Giada, Gayer-Anderson, Charlotte, Morgan, Craig, Sami, Musa B, Sham, Pak, de Haan, Lieuwe, Velthorst, Eva, Jongsma, Hannah E, Kirkbride, James B, Rutten, Bart P F, Richards, Alexander L, Roldan, Laura, Arango, Celso, Bernardo, Miquel, Bobes, Julio, Sanjuan, Julio, Santos, Jose Luis, Arrojo, Manuel, Tarricone, Ilaria, Tortelli, Andrea, Szöke, Andrei, Del-Ben, Cristina Marta, Selten, Jean-Paul, Lynskey, Michael, Jones, Peter B, Van Os, Jim, La Barbera, Daniele, Murray, Robin M, Di Forti, Marta
- Database ID:
- RTHC-02551
Evidence Hierarchy
Compares people with a condition to similar people without it.
What do these levels mean? →Frequently Asked Questions
Does cannabis make people with psychosis smarter?
No. The study found that psychosis patients who used cannabis were already more socially functional before becoming ill. Their better social skills likely made them more likely to be in situations where cannabis was available.
What about the IQ difference?
Occasional cannabis users (both patients and controls) had IQ scores about 3 points higher than never-users. This small difference was not specific to psychosis and may reflect broader socioeconomic or social factors.
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Cite This Study
https://rethinkthc.com/research/RTHC-02551APA
Ferraro, Laura; La Cascia, Caterina; Quattrone, Diego; Sideli, Lucia; Matranga, Domenica; Capuccio, Veronica; Tripoli, Giada; Gayer-Anderson, Charlotte; Morgan, Craig; Sami, Musa B; Sham, Pak; de Haan, Lieuwe; Velthorst, Eva; Jongsma, Hannah E; Kirkbride, James B; Rutten, Bart P F; Richards, Alexander L; Roldan, Laura; Arango, Celso; Bernardo, Miquel; Bobes, Julio; Sanjuan, Julio; Santos, Jose Luis; Arrojo, Manuel; Tarricone, Ilaria; Tortelli, Andrea; Szöke, Andrei; Del-Ben, Cristina Marta; Selten, Jean-Paul; Lynskey, Michael; Jones, Peter B; Van Os, Jim; La Barbera, Daniele; Murray, Robin M; Di Forti, Marta. (2020). Premorbid Adjustment and IQ in Patients With First-Episode Psychosis: A Multisite Case-Control Study of Their Relationship With Cannabis Use.. Schizophrenia bulletin, 46(3), 517-529. https://doi.org/10.1093/schbul/sbz077
MLA
Ferraro, Laura, et al. "Premorbid Adjustment and IQ in Patients With First-Episode Psychosis: A Multisite Case-Control Study of Their Relationship With Cannabis Use.." Schizophrenia bulletin, 2020. https://doi.org/10.1093/schbul/sbz077
RethinkTHC
RethinkTHC Research Database. "Premorbid Adjustment and IQ in Patients With First-Episode P..." RTHC-02551. Retrieved from https://rethinkthc.com/research/ferraro-2020-premorbid-adjustment-and-iq
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.