One of the more striking revelations of the review is that the link between cannabis and violence is not a one-way street. The data showed that cannabis users do not only have a higher propensity for aggression but are also significantly more likely to be on the receiving end of violent acts. According to the review, people who used cannabis were approximately one and a half times as likely to become victims of violence compared to non-users.
The researchers found that this association with victimization was notably stronger among women than among men. While the study does not definitively explain why this disparity exists, it points to a vulnerability that warrants further investigation by social scientists and public health officials. This aspect of the research highlights the social consequences of drug use, suggesting that the risks extend into the personal safety and domestic lives of users.
Professor Sir Robin Murray, the study’s senior author and a Professor of Psychiatric Research at the IoPPN, provided a detailed breakdown of the statistical risks across different segments of society. He noted that the increased risk of violence was present regardless of whether an individual was already involved in the mental health system.
"In the general population, people who used cannabis were around twice as likely to have committed a violent act as those who didn’t," Sir Robin stated. He further explained that for those already receiving psychiatric care, the association was even more pronounced: "For those in psychiatric care, cannabis users were around two and a half times as likely to be violent as other psychiatric patients who didn’t use cannabis."
The review also examined the longevity of this link. While the association remained present in longitudinal studies—those that follow the same individuals over a long period—the effect was slightly smaller than in cross-sectional studies, which look at a single point in time. However, the most dramatic statistics appeared when the researchers looked at the legal consequences of violence. For acts that resulted in a criminal conviction, individuals who used cannabis were three to four times as likely to have been convicted than their non-using counterparts.
Sir Robin emphasized that these findings arrive at a critical juncture in global drug policy. "As cannabis becomes more commercialized and legalized around the world, the conversation about its risks has focused mostly on the person using it," he said. "This review shows that violence, both committing it and experiencing it, needs to be part of that conversation too."
Implications for Mental Health and Public Health
The findings carry significant weight for the future of mental health treatment and public safety policy. The researchers argue that the evidence is now strong enough to warrant changes in how medical professionals interact with their patients. Specifically, they recommend that mental health services should integrate routine inquiries about cannabis use into their standard risk assessments. By identifying cannabis use early, clinicians may be better equipped to evaluate a person’s risk of engaging in or being subjected to violence, potentially allowing for earlier intervention.
