Cannabis use ups physical violence in youths

Use of cannabis is moderately associated with physical violence, and this association remains significant regardless of study design and adjustment for confounding factors, such as socioeconomic factors and other substance use, suggests a study.

The investigators searched the databases of PubMed, PsycINFO, Web of Science, and Google Scholar for articles published from the inception to July 2019. Studies included were those that examined both cannabis use and the perpetration of physical violence in a sample of youths and young adults aged <30 years. A random-effects model was used for the meta-analysis.

Egger’s test was used to assess the risk of publication bias. Guidelines from the Meta-Analysis of Observational Studies in Epidemiology were followed.

A total of 11,348 potential studies were screened, of which 30 were included, yielding 296,815 adolescents and young adults. The pooled studies showed an odds ratio [OR] of 2.11 (95 percent confidence interval [CI], 1.64–2.72). The pooled ORs for cross-sectional and longitudinal studies were 2.15 (95 percent CI, 1.58–2.94) and 2.02 (95 percent CI, 1.26–3.23), respectively.

Preliminary evidence suggested a higher risk of violence among persistent heavy users (OR, 2.81, 95 percent CI, 1.68–4.74) than past-year users (OR, 2.05, 95 percent CI, 1.5–2.8) and lifetime users (OR, 1.94, 95 percent CI, 1.29–2.93). Unadjusted studies had an OR of 2.62 (95 percent CI, 1.89–3.62), while those reporting estimates adjusted for potential confounding factors had an OR of 2.01 (95 percent CI, 1.57–2.56).

“Cannabis use in this population is a risk factor for violence,” the investigators said.