Cannabis users more likely to commit and experience violence, review finds

People who use cannabis are more likely to commit violent acts and roughly one and a half times as likely to experience violence themselves, according to a systematic review and meta-analysis published in the journal Psychological Medicine. Researchers at King’s College London analyzed data from 63 studies involving more than 265,000 individuals to evaluate the association between cannabis consumption and violent behavior or victimization. As a clinician, I’ve seen how heavy cannabis use can be a factor in violence, said Dr. Marta Di Forti, co-author of the study from the Institute of Psychiatry, Psychology & Neuroscience at King’s College London and the South London and Maudsley NHS Foundation Trust. Our team has long exercised restraint regarding how openly we discussed this connection, but an analysis of this magnitude enables us to address the hazards more definitively while making sure not to unfairly target the wider population of cannabis consumers.

Evaluating 63 Studies on Cannabis and Violence

The research team at the Institute of Psychiatry, Psychology & Neuroscience combined global study data to examine both self-reported violence and instances resulting in criminal convictions. The review utilized the World Health Organization definition of violence, which encompasses physical, sexual, and psychological acts directed at another person, occurring both within and outside intimate relationships. When individual studies measured multiple forms of violence, researchers focused strictly on the most serious type reported. For violence that led to a formal criminal conviction, individuals who used cannabis were three to four times as likely to have been convicted. The investigation also revealed distinct gender patterns regarding victimization. The association indicating that cannabis users were about one and a half times as likely to become victims of violence proved stronger among women than among men.

Mental Health Services Should Incorporate Cannabis Use Risk Profiles

The authors argue that clinical practices and public messaging must adapt to incorporate these findings. Mental health services should routinely ask about cannabis use when evaluating a patient’s risk profile for violence, according to the study authors. Public health information regarding cannabis should include the documented connection to violence.

Despite the strong statistical associations, the researchers emphasize a critical scientific distinction: the review identifies a correlation and does not prove that cannabis directly causes violence. Cannabis use frequently co-occurs with other risk-augmenting elements, including alcohol consumption, the use of other illicit substances, and challenging social circumstances.

Only a small number of the analyzed studies quantified the exact dosage or frequency of cannabis consumption. Findings involving criminal convictions derived from a relatively limited subset of papers, and most underlying research was conducted prior to the widespread commercial availability of high-potency cannabis strains.

With cannabis facing fewer legal barriers and seeing greater commercial availability globally, discussions regarding its potential dangers have typically centered entirely on the individual consumer. This new paper demonstrates that both the perpetration and victimization aspects of violence must be integrated into those ongoing discussions as well.