Starting cannabis before age 15 quadrupled violence risk in early psychosis patients
Among 265 early psychosis patients, those who started using cannabis before age 15 had 4.5 times the odds of violent behavior, even after adjusting for other risk factors.
Quick Facts
What This Study Found
In a 36-month prospective cohort of 265 early psychosis patients, violent patients began cannabis use at an average age of 15.3 vs. 17.0 for nonviolent patients (p=0.004). Early-onset cannabis use (before age 15) was an independent risk factor for violent behavior (OR 4.47, CI 1.13-20.06) after adjustment for age, other substance use, and known violence risk factors.
Key Numbers
265 patients; 72 violent, 193 nonviolent; violent started cannabis at 15.3 vs 17.0; early onset (≤15) OR 4.47 (1.13-20.06) for violence; 36-month follow-up.
How They Did This
Prospective cohort study following 265 early psychosis patients (ages 18-35) for 36 months, using logistic regression to assess link between age of cannabis onset and violent behavior, adjusting for multiple covariates.
Why This Research Matters
Violence in psychosis is a serious clinical and public health concern. Identifying early cannabis use as an independent risk factor suggests a modifiable target for prevention.
The Bigger Picture
This adds to evidence that the timing of cannabis exposure matters as much as whether someone uses at all. The adolescent brain may be particularly vulnerable to cannabis effects that increase later aggression in the context of psychosis.
What This Study Doesn't Tell Us
Wide confidence interval (1.13-20.06) suggests imprecision; age of cannabis onset was self-reported; violence was broadly defined; cannot prove causation; relatively small sample for subgroup analysis.
Questions This Raises
- ?Would delaying cannabis initiation even by 1-2 years reduce violence risk in psychosis-prone youth?
- ?What mechanism connects early cannabis use to later violence?
Trust & Context
- Key Stat:
- Cannabis before age 15: 4.5x higher violence odds in psychosis (OR 4.47)
- Evidence Grade:
- Moderate: prospective design with appropriate adjustments, but wide confidence interval and self-reported exposure.
- Study Age:
- Published 2020.
- Original Title:
- Early onset of cannabis use and violent behavior in psychosis.
- Published In:
- European psychiatry : the journal of the Association of European Psychiatrists, 63(1), e78 (2020)
- Authors:
- Moulin, Valerie(3), Alameda, Luis(9), Framorando, David(2), Baumann, Philipp-S, Gholam, Mehdi, Gasser, Jacques, Do Cuenod, Kim-Q, Conus, Philippe
- Database ID:
- RTHC-02733
Evidence Hierarchy
Enrolls participants and follows them forward in time.
What do these levels mean? →Frequently Asked Questions
Does the age of first cannabis use matter for violence risk?
Yes. In this study, starting before age 15 was associated with 4.5 times higher odds of violent behavior in early psychosis patients, even after controlling for other risk factors.
Is cannabis use itself the risk factor, or just early use?
Being a cannabis user vs. non-user was controlled for in the analysis. It was specifically the early onset (before 15) that emerged as the independent risk factor for violence.
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Cite This Study
https://rethinkthc.com/research/RTHC-02733APA
Moulin, Valerie; Alameda, Luis; Framorando, David; Baumann, Philipp-S; Gholam, Mehdi; Gasser, Jacques; Do Cuenod, Kim-Q; Conus, Philippe. (2020). Early onset of cannabis use and violent behavior in psychosis.. European psychiatry : the journal of the Association of European Psychiatrists, 63(1), e78. https://doi.org/10.1192/j.eurpsy.2020.71
MLA
Moulin, Valerie, et al. "Early onset of cannabis use and violent behavior in psychosis.." European psychiatry : the journal of the Association of European Psychiatrists, 2020. https://doi.org/10.1192/j.eurpsy.2020.71
RethinkTHC
RethinkTHC Research Database. "Early onset of cannabis use and violent behavior in psychosi..." RTHC-02733. Retrieved from https://rethinkthc.com/research/moulin-2020-early-onset-of-cannabis
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.