Meta-Analysis of 63 Studies Links Cannabis Use to Elevated Violence Perpetration and Victimization Risks
Meta-analysis shows cannabis use associated with roughly doubled violence perpetration risk and elevated victimization, strongest for convictions and psychiatric patients. Associations persist longitudinally but remain vulnerable to confounding; high-potency products may intensify effects not captured in older data. Findings support screening in clinical risk assessments while underscoring need for better-controlled longitudinal research.
The King's College London team pooled observational data across general and clinical populations, separating self-reported violence from criminal convictions and applying WHO definitions that encompass physical, sexual, and psychological acts. Pooled odds ratios reached 2.0 in community samples and 2.5 among psychiatric patients; conviction-linked risks were 3- to 4-fold higher, though derived from fewer studies. Longitudinal subsets showed attenuated yet persistent signals, indicating temporal ordering but residual confounding by polysubstance use and socioeconomic adversity.
Commercialization and rising THC potency since most included studies were conducted suggest current daily use may amplify effects beyond the observed associations. The review also documented elevated victimization, particularly among women, underscoring bidirectional pathways that public-health messaging on legalization has largely omitted. Routine cannabis screening in violence-risk assessments within mental-health services is therefore recommended, yet implementation requires disentangling cannabis-specific contributions from co-occurring alcohol and stimulant use.
Next steps include prospective cohorts tracking high-potency products with granular dose and frequency measures, plus Mendelian randomization to test causality while adjusting for genetic liability to aggression and substance dependence. Regulatory evaluations of cannabis markets should incorporate violence endpoints alongside psychosis outcomes to inform potency caps and age restrictions.
Di Forti: Prospective cohorts using daily high-potency cannabis will report adjusted HR >3.0 for violence within five years.
Sources (3)
- [1]Primary Source(https://www.cambridge.org/core/journals/psychological-medicine/article/cannabis-use-is-associated-with-increased-risk-of-violence-a-systematic-review-and-metaanalysis/10.1017/S0033291726105856)
- [2]Supporting Source(https://www.thelancet.com/journals/lanpsy/article/PIIS2215-0366(19)30048-3/fulltext)
- [3]Supporting Source(https://jamanetwork.com/journals/jamapsychiatry/fullarticle/2787695)