Areas With More Teen Cannabis Use Had Higher Rates of First Psychotic Episodes
In an Italian region, area-level frequent cannabis use among 15-19 year-olds was associated with higher first-episode psychosis incidence and longer delays before treatment, alongside educational deprivation and population density.
Quick Facts
What This Study Found
Frequent cannabis use among teens (area-level) was associated with increased first-episode psychosis incidence (IRR=1.31). Cannabis use also increased the duration of untreated psychosis by an average of 12.9 months. Educational deprivation (IRR=1.15) and population density (IRR=1.14) also independently predicted FEP incidence.
Key Numbers
1,240 FEP cases across 331 municipalities. Cannabis use IRR for FEP: 1.31 (95% CrI: 0.98-1.82). Cannabis increased DUP by 12.9 months. Educational deprivation IRR: 1.15. Population density IRR: 1.14.
How They Did This
Prospective analysis of 1,240 individuals aged 18-35 with first-episode psychosis from an early detection program in Emilia-Romagna, Italy. Area-level exposures from 331 municipalities were modeled using Bayesian hierarchical models informed by a directed acyclic graph for causal assumptions.
Why This Research Matters
This study goes beyond individual-level associations to show that community-level cannabis availability affects psychosis rates. The finding that cannabis delays treatment-seeking is particularly concerning for outcomes.
The Bigger Picture
Community-level factors like cannabis availability, educational environment, and urbanicity all independently influence psychosis risk. This ecological perspective suggests that population-level interventions targeting multiple factors could reduce psychosis incidence.
What This Study Doesn't Tell Us
Area-level cannabis use is a proxy that may not reflect individual exposure. The cannabis IRR confidence interval crossed 1.0 (0.98-1.82). Italian setting may not generalize. Ecological study cannot prove individual-level causation.
Questions This Raises
- ?Would reducing teen cannabis access at the community level decrease FEP incidence?
- ?Why does cannabis availability delay treatment-seeking?
- ?How do these area-level factors interact?
Trust & Context
- Key Stat:
- 12.9 months longer untreated psychosis in areas with more cannabis use
- Evidence Grade:
- Moderate: prospective population-based study with sophisticated Bayesian modeling, but ecological exposure measurement and borderline significance for the cannabis-incidence association
- Study Age:
- Published in 2025
- Original Title:
- The impact of socioeconomic factors on the incidence and characteristics of first-episode psychosis.
- Published In:
- Epidemiology and psychiatric sciences, 34, e45 (2025)
- Authors:
- Belvederi Murri, Martino(2), Onofrio, Alice, Punzi, Chiara, Caranci, Nicola, Rubolino, Enrico, Giovinazzi, Francesco, Azzolina, Danila, Folesani, Federica, Grassi, Luigi, Tarricone, Ilaria, Starace, Fabrizio
- Database ID:
- RTHC-06043
Evidence Hierarchy
Enrolls participants and follows them forward in time.
What do these levels mean? →Frequently Asked Questions
Does community cannabis use affect psychosis rates?
This study found that areas with higher rates of frequent cannabis use among 15-19 year-olds had higher first-episode psychosis incidence, though the confidence interval was borderline (0.98-1.82). More clearly, higher cannabis use areas had significantly longer delays before psychosis treatment.
What other community factors affected psychosis risk?
Educational deprivation and population density also independently predicted higher psychosis incidence. The study used a causal modeling approach to disentangle these overlapping community-level influences.
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Cite This Study
https://rethinkthc.com/research/RTHC-06043APA
Belvederi Murri, Martino; Onofrio, Alice; Punzi, Chiara; Caranci, Nicola; Rubolino, Enrico; Giovinazzi, Francesco; Azzolina, Danila; Folesani, Federica; Grassi, Luigi; Tarricone, Ilaria; Starace, Fabrizio. (2025). The impact of socioeconomic factors on the incidence and characteristics of first-episode psychosis.. Epidemiology and psychiatric sciences, 34, e45. https://doi.org/10.1017/S2045796025100206
MLA
Belvederi Murri, Martino, et al. "The impact of socioeconomic factors on the incidence and characteristics of first-episode psychosis.." Epidemiology and psychiatric sciences, 2025. https://doi.org/10.1017/S2045796025100206
RethinkTHC
RethinkTHC Research Database. "The impact of socioeconomic factors on the incidence and cha..." RTHC-06043. Retrieved from https://rethinkthc.com/research/belvederi-2025-the-impact-of-socioeconomic
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.