A recent systematic review and meta-analysis, published in Psychological Medicine, indicates that cannabis users may have about twice the odds of committing violence.
Professor Simon Moore, Director of the Violence Research Group at Cardiff University, noted that the meta-analysis did not investigate the specific contexts of cannabis use, such as location, companions, or exposure to violent environments. He highlighted that studies tracking individuals over time showed a significantly smaller association, suggesting that unmeasured circumstances could contribute to the larger associations observed in cross-sectional studies.
Professor Moore added that factors like peer group or neighbourhood could potentially account for the longitudinal estimate entirely. He concluded that without this information, the review cannot definitively state whether cannabis itself or the environments in which it is used explain the observed violence.