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Cannabis users were twice as likely to commit violence, review finds | ScienceDaily (opens in a new tab)

sciencedaily.com · 2026-09-30

Short answerEvidenceSource

Short answer

Mixed

Mixed.

The claims we could check match the study, but some claims were not covered by the evidence reviewed.

  • 3 supported
  • 2 not covered

Checked against the study summary. The full text wasn't available, so some details couldn't be settled either way.

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Follow the evidence trail
1
2

NewsLink checks it

Mixed

Every claim we could check holds up. Three of five claims match the study. This overall rating is based only on the claims we could check. Two claims the study doesn't address.

  • 3 supported
  • 2 not covered
Open claim evidence
3
Then inspect each claim

Evidence layer

Claim by claim

Each claim gets a verdict. Expand it to see the evidence directly below.

5 claims in this story

Showing all 5 claimsChoose a verdict to focus the list.

Claim 1 of 5Not coveredThe researchers say the review does not prove cannabis directly causes violence and that other factors such as alcohol use, other drug use, and difficult social circumstances may also contribute.View evidenceHide evidence

Why this verdict

The general caveat that the evidence is associational and does not establish direct causation is consistent with the observational cross-sectional/longitudinal evidence described in the profile. However, the abstract-level paper profile does not verify the specific attributed caveats about alcohol use, other drug use, or difficult social circumstances, nor the exact wording that the researchers said this.

1

Study evidence

In psychiatric patient samples, cannabis use was associated with higher odds of perpetrating violence.OR 2.49 (95% CI 1.72–3.61)

“This meta-analysis, conducted according to PRISMA guidelines, synthesized evidence from 63 peer-reviewed studies (N = 265,079) identified via MEDLINE, EMBASE, and PsycINFO searches up to November 2024”
2

Study evidence

Cannabis use was associated with increased odds of becoming a victim of violence (pooled OR 1.49, 95% CI 1.38–1.60); the increase in risk was reported as more pronounced in female and mixed-gender cohorts versus males.OR 1.49 (95% CI 1.38–1.60)

“Furthermore, cannabis use was significantly associated with an increased risk of becoming a victim of violence (OR 1.49, 95% CI 1.38-1.60), a risk more pronounced in females and mixed-gender cohorts compared to males.”
Claim 2 of 5Not coveredThe study was a systematic review and meta-analysis of 63 studies and was published in Psychological Medicine.View evidenceHide evidence

As stated63 studies

Why this verdict

The systematic review/meta-analysis design and 63-study count are supported by the profile. The publication venue, Psychological Medicine, is not present in the supplied abstract-level paper profile, so that part is not verifiable at this depth.

1

Study evidence

In psychiatric patient samples, cannabis use was associated with higher odds of perpetrating violence.OR 2.49 (95% CI 1.72–3.61)

“This meta-analysis, conducted according to PRISMA guidelines, synthesized evidence from 63 peer-reviewed studies (N = 265,079) identified via MEDLINE, EMBASE, and PsycINFO searches up to November 2024”
Claim 3 of 5SupportedA review of more than 265,000 people found that cannabis use was associated with higher rates of both committing violence and becoming a victim of it.View evidenceHide evidence

As statedmore than 265,000 people

Why this verdict

The abstract-level profile reports a PRISMA-guided systematic review/meta-analysis of 63 studies with N=265,079 and finds cannabis use associated with increased risk of both perpetrating violent acts and becoming a victim of violence. The story frames this as an association rather than causation.

1

Study evidence

In psychiatric patient samples, cannabis use was associated with higher odds of perpetrating violence.OR 2.49 (95% CI 1.72–3.61)

“This meta-analysis, conducted according to PRISMA guidelines, synthesized evidence from 63 peer-reviewed studies (N = 265,079) identified via MEDLINE, EMBASE, and PsycINFO searches up to November 2024”
2

Study evidence

Cannabis use was associated with increased odds of becoming a victim of violence (pooled OR 1.49, 95% CI 1.38–1.60); the increase in risk was reported as more pronounced in female and mixed-gender cohorts versus males.OR 1.49 (95% CI 1.38–1.60)

“Furthermore, cannabis use was significantly associated with an increased risk of becoming a victim of violence (OR 1.49, 95% CI 1.38-1.60), a risk more pronounced in females and mixed-gender cohorts compared to males.”
Claim 4 of 5SupportedIn the general population, people who used cannabis were around twice as likely to have committed a violent act as those who did not, and people in psychiatric care who used cannabis were around two and a half times as likely to be violent as other psychiatric patients who did not use cannabis.View evidenceHide evidence

As statedaround twice as likely; around two and a half times as likely

Why this verdict

The paper profile reports elevated odds of perpetrating violence in the general population, OR 2.05, and in psychiatric patient samples, OR 2.49. The story's 'around twice' and 'around two and a half times' wording matches these abstract-level estimates, though the paper reports odds ratios rather than direct risk ratios.

1

Study evidence

In psychiatric patient samples, cannabis use was associated with higher odds of perpetrating violence.OR 2.49 (95% CI 1.72–3.61)

“This meta-analysis, conducted according to PRISMA guidelines, synthesized evidence from 63 peer-reviewed studies (N = 265,079) identified via MEDLINE, EMBASE, and PsycINFO searches up to November 2024”
Claim 5 of 5SupportedPeople who used cannabis were about one and a half times as likely to become victims of violence, with the association reported as stronger among women than among men.View evidenceHide evidence

As statedabout one and a half times as likely

Why this verdict

The paper profile reports cannabis use associated with increased odds of victimization, OR 1.49, and says the association was more pronounced in female and mixed-gender cohorts than in male cohorts. The story's 'about one and a half times' and stronger association among women than men is consistent at abstract depth, though the paper reports odds ratios.

1

Study evidence

Cannabis use was associated with increased odds of becoming a victim of violence (pooled OR 1.49, 95% CI 1.38–1.60); the increase in risk was reported as more pronounced in female and mixed-gender cohorts versus males.OR 1.49 (95% CI 1.38–1.60)

“Furthermore, cannabis use was significantly associated with an increased risk of becoming a victim of violence (OR 1.49, 95% CI 1.38-1.60), a risk more pronounced in females and mixed-gender cohorts compared to males.”
Then look for missing context

Context layer

What the story left out

Important study details the story did not include.

  • The association with perpetration remained statistically significant in longitudinal studies but was much smaller there, OR 1.17, than in cross-sectional studies, OR 2.37.

    This design-specific pattern is a material qualifier for temporality and causal interpretation. The story mentions association and confounding caveats, but it does not report the smaller longitudinal estimate or the difference between longitudinal and cross-sectional findings.

    From PRISMA-guided systematic review and random-effects meta-analysis

  • Violence resulting in criminal conviction showed especially large associations with cannabis use in both general-population and psychiatric samples.

    The paper profile highlights criminal-conviction outcomes as a notable subgroup result, with OR 3.75 in general-population samples and OR 4.21 in psychiatric samples. The story caveats mention limited conviction evidence, but the presented claims do not report this larger-effect subgroup finding.

    From PRISMA-guided systematic review and random-effects meta-analysis

  • The authors draw interpretive implications that cannabis use may be a target for interventions to reduce violence and that routine assessment of cannabis use is needed among psychiatric patients.

    The story focuses on the association and limitations, but does not cover the paper's abstract-level practice/intervention implications.

    From Narrative interpretation of meta-analysis findings

  • At abstract depth, the profile does not provide detailed heterogeneity statistics, study-level risk-of-bias assessment, or detailed definitions/measurement of victimization across studies.

    These are material evidence-quality details noted as unavailable in the supplied profile. The story mentions several limitations, but not heterogeneity, risk of bias, or variation in outcome definitions/measurement.

    From PRISMA-guided systematic review and random-effects meta-analysis; systematic review and random-effects meta-analysis

4 things the story did carry across
  • The paper is a PRISMA-guided systematic review and random-effects meta-analysis of 63 peer-reviewed studies with an overall N=265,079.
  • Cannabis use was associated with higher odds of perpetrating violence in both general-population samples and psychiatric patient samples, with pooled estimates of OR 2.05 and OR 2.49 respectively.
  • Cannabis use was associated with increased odds of becoming a victim of violence, OR 1.49, with the association more pronounced in female and mixed-gender cohorts than in male cohorts.
  • Causal inference is limited because the included evidence is observational and includes cross-sectional as well as longitudinal designs; study-level confounding control is not detailed in the abstract-level profile.
Then read the study layer

Study layer

Study at a glance

Scan the study first. Expand only the parts you want to inspect.

Pieces of work

3

Evidence read

study summary

Lead result

secondary data

1Lead resultsecondary dataQuantify the association between cannabis use and risk of perpetrating violence across included studies, overall and by key subgroups (psychiatric vs general population; longitudinal vs cross-sectional; outcome severity such as criminal conviction).PRISMA-guided systematic review and random-effects meta-analysisExpand

In plain English

PRISMA-guided systematic review and random-effects meta-analysis of 63 studies (N = 265,079) found that cannabis use is associated with increased risk of perpetrating violent acts across populations and study designs, with particularly large associations for violence resulting in criminal conviction; cannabis use was also associated with increased risk of becoming a victim of violence.

Key findings

  • In psychiatric patient samples, cannabis use was associated with higher odds of perpetrating violence.OR 2.49 (95% CI 1.72–3.61)
  • In general population samples, cannabis use was associated with higher odds of perpetrating violence.OR 2.05 (95% CI 1.74–2.41)
“This meta-analysis, conducted according to PRISMA guidelines, synthesized evidence from 63 peer-reviewed studies (N = 265,079) identified via MEDLINE, EMBASE, and PsycINFO searches up to November 2024”
2secondary dataQuantify the association between cannabis use and risk of becoming a victim of violence, including subgroup patterns (e.g., by sex composition of cohorts).systematic review and random-effects meta-analysisExpand

In plain English

PRISMA-guided systematic review and random-effects meta-analysis (63 studies, N = 265,079 reported overall) found cannabis use associated with increased odds of becoming a victim of violence (pooled OR 1.49, 95% CI 1.38–1.60). The association was reported as more pronounced in female and mixed-gender cohorts than in male cohorts.

Key findings

  • Cannabis use was associated with increased odds of becoming a victim of violence (pooled OR 1.49, 95% CI 1.38–1.60); the increase in risk was reported as more pronounced in female and mixed-gender cohorts versus males.OR 1.49 (95% CI 1.38–1.60)
“Furthermore, cannabis use was significantly associated with an increased risk of becoming a victim of violence (OR 1.49, 95% CI 1.38-1.60), a risk more pronounced in females and mixed-gender cohorts compared to males.”
What this piece can’t prove
  • Abstract does not report study-level heterogeneity measures, detailed risk-of-bias assessments, or how victimization was defined/measured across included studies.

1 further detail could not be confirmed from the summary.

3otherProvide synthesis-based implications for prevention/assessment (e.g., cannabis use as an intervention target; routine assessment in psychiatric patients).Narrative interpretation of meta-analysis findingsExpand

In plain English

The authors interpret their meta-analytic findings to suggest that cannabis use could be a modifiable target for interventions to reduce violence and that routine assessment of cannabis use should be considered among psychiatric patients.

Key findings

  • The paper highlights the potential for targeting cannabis use with interventions as a way to decrease violence.
  • The paper underscores the need for routine assessment of cannabis use among psychiatric patients.
“It also highlights the potential of cannabis use as a target for interventions to decrease violence, and underscores the need for routine assessment of cannabis use among psychiatric patients.”
What this piece can’t prove
  • The abstract does not provide implementation details, criteria for assessment, or downstream clinical pathways tied to routine assessment.

2 further details could not be confirmed from the summary.

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Method layer

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Papers considered

The selected paper, plus nearby candidates.

PubMed, Europe PMC, Crossref · 37 candidate papers

And 31 more candidates considered.