Lower homeownership rates and higher prevalence of daily cannabis use each independently contributed to variation in psychosis incidence across 14 European settings.
People interested in the relationship between cannabis use, social factors, and psychosis risk.
53% higher affective psychosis incidence in settings with more daily cannabis use
What the researchers found
Lower owner-occupancy was independently associated with increased first-episode psychosis incidence (aIRR: 0.76) and non-affective psychosis (aIRR: 0.68). Daily cannabis use prevalence was associated with affective psychosis incidence (aIRR: 1.53). High-potency cannabis use was not independently associated with psychosis incidence after adjustment.
Why it matters
This is one of the first studies to examine both social deprivation and cannabis use simultaneously as predictors of psychosis incidence across multiple settings. The finding that both factors contribute independently suggests neither alone explains the variation in psychosis rates.
The numbers in context
Data from 14 European settings. Lower owner-occupancy aIRR: 0.76 (95% CI: 0.61-0.95) for all FEP. Daily cannabis use aIRR: 1.53 (95% CI: 1.02-2.31) for affective psychosis. No association found with unemployment or high-potency cannabis use prevalence.
How the study worked
Researchers used incidence data from 14 settings in the EU-GEI study for people aged 18-64. Cannabis use prevalence was estimated from population controls with multiple imputation for missing data. Negative binomial regression modeled psychosis incidence while controlling for population density, age, sex, and migrant/ethnic group.
What this study cannot tell us
Ecological study design means individual-level conclusions cannot be drawn. Cannabis use prevalence was estimated from controls, not directly measured in the population. Cross-sectional design limits causal inference. Only 14 settings were included.
How to read the evidence
Multi-site European study with rigorous statistical adjustment, though the ecological design and estimated cannabis prevalence measures limit causal interpretation.
When this study was published
Published in 2024 in Schizophrenia Bulletin using EU-GEI study data.
The bigger picture
The debate about whether cannabis causes psychosis often overlooks the social context in which cannabis use occurs. This study highlights that neighborhood-level poverty and cannabis use patterns are both relevant, and that public health interventions targeting either factor could potentially reduce psychosis burden.
Questions still open
- Why was daily cannabis use associated with affective but not non-affective psychosis? Does social deprivation increase cannabis use, increase psychosis risk independently, or both? Would similar patterns emerge in non-European settings?
Common questions
Does cannabis cause psychosis?
Was high-potency cannabis more strongly linked to psychosis?
Read the original research
The Role of Social Deprivation and Cannabis Use in Explaining Variation in the Incidence of Psychotic Disorders: Findings From the EU-GEI Study.
Schizophrenia bulletin, 50(5), 1039-1049
Citation
Brink, Vera; Andleeb, Humma; Gayer-Anderson, Charlotte; Arango, Celso; Arrojo, Manuel; Berardi, Domenico; Bernardo, Miquel; Bobes, Julio; Del-Ben, Cristina Marta; Ferraro, Laura; de Haan, Lieuwe; La Barbera, Daniele; La Cascia, Caterina; Lasalvia, Antonio; Llorca, Pierre-Michel; Menezes, Paolo Rossi; Pignon, Baptiste; Sanjuán, Julio; Santos, José Luis; Selten, Jean-Paul; Tarricone, Ilaria; Tortelli, Andrea; Tripoli, Giada; Velthorst, Eva; Rutten, Bart P F; van Os, Jim; Quattrone, Diego; Murray, Robin M; Jones, Peter B; Morgan, Craig; Di Forti, Marta; Jongsma, Hannah E; Kirkbride, James B. (2024). The Role of Social Deprivation and Cannabis Use in Explaining Variation in the Incidence of Psychotic Disorders: Findings From the EU-GEI Study.. Schizophrenia bulletin, 50(5), 1039-1049. https://doi.org/10.1093/schbul/sbae072
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