First-episode psychosis patients with the most cognitive deterioration had higher cannabis exposure and more environmental risk factors than those who maintained cognitive function.
Psychiatrists and psychologists working with early psychosis; researchers studying cannabis and cognitive outcomes.
Deteriorating cluster had significantly higher cannabis exposure than same-IQ peers
What the researchers found
Among 802 first-episode psychosis patients, those in the "deteriorating" cognitive cluster had higher cannabis exposure than the "intermediate" cluster with identical IQ, and all patient clusters had higher environmental risk scores than the 1,263 community controls.
Why it matters
This study helps untangle why some people with psychosis experience cognitive decline while others maintain function. Cannabis exposure emerged as one distinguishing factor, separate from baseline intelligence.
The numbers in context
802 FEP patients clustered into: high-functioning (n=205), low-functioning (n=223), intermediate (n=224), deteriorating (n=150). Deteriorating cluster had higher cannabis exposure than intermediate (mean difference=0.48, 95% CI 0.49-0.91). ERS highest in deteriorating cluster (beta=2.8, 95% CI 2.3-3.4).
How the study worked
Cross-sectional analysis from the EU-GEI study comparing cognitive clusters of 802 first-episode psychosis patients and 1,263 controls. Used the Maudsley Environmental Risk Score (ERS) combining paternal age, childhood adversities, cannabis use, and ethnic minority status.
What this study cannot tell us
Cross-sectional design cannot establish causation. Environmental risk score combines multiple factors. Cognitive clusters derived from single timepoint assessment. Cannabis exposure was one component of a composite score.
How to read the evidence
Large multi-site study (EU-GEI) but cross-sectional, limiting causal conclusions.
When this study was published
2025 study
The bigger picture
Identifying modifiable risk factors like cannabis use that contribute to cognitive deterioration in psychosis opens the door to targeted early interventions that could preserve cognitive function.
Questions still open
- Would reducing cannabis exposure before psychosis onset prevent cognitive deterioration? Are the cognitive trajectories reversible with intervention?
Common questions
What does "deteriorating cluster" mean?
Does this prove cannabis causes cognitive decline in psychosis?
Read the original research
Cognitive presentation at psychosis onset through premorbid deterioration and exposure to environmental risk factors.
Psychological medicine, 55, e12
Citation
Ferraro, Laura; Di Forti, Marta; La Barbera, Daniele; La Cascia, Caterina; Morgan, Craig; Tripoli, Giada; Jongsma, Hannah; Seminerio, Fabio; Sartorio, Crocettarachele; Sideli, Lucia; Tarricone, Ilaria; Carloni, Anna Lisa; Szoke, Andrei; Pignon, Baptiste; Bernardo, Miguel; de Haan, Lieuwe; Arango, Celso; Velthorst, Eva; Gayer-Anderson, Charlotte; Kirkbride, James; Rutten, Bart P F; Lasalvia, Antonio; Tosato, Sarah; Del Ben, Cristina Marta; Menezes, Paulo Rossi; Bobes, Julio; Arrojo, Manuel; Tortelli, Andrea; Jones, Peter; Selten, Jean-Paul; van Os, Jim; Murray, Robin; Quattrone, Diego; Vassos, Evangelos. (2025). Cognitive presentation at psychosis onset through premorbid deterioration and exposure to environmental risk factors.. Psychological medicine, 55, e12. https://doi.org/10.1017/S0033291724003507
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