Does Marijuana Use Lead to Violent Behavior?

In the wake of a spate of mass shootings, anti-pot legislators are blaming marijuana, video games, mental health, and everything else but gun accessibility for the seeming increase in gun violence in the United States. In fact, other countries have even issued travel warnings to their citizens about “the potential for gunfire incidents” if they visit the U.S. While marijuana use isn’t entirely risk-free, research has far from confirmed a link between cannabis use and violence.

55 million Americans have tried cannabis at least once in their lives and 35 million are regular users who consume at least once or twice a month. While cannabis legalization has increased in recent years, violent crime has drastically reduced over the past quarter-century. Much of the scientific evidence points to a reduction in violence after legalization, but a lack of long-term studies has muddled the debate.

Marijuana Decriminalization Lowers Severe Injuries

Despite the hemming and hawing from weed alarmists, studies have found that marijuana decriminalization actually reduces violence. One study found that cannabis decriminalization has lowered violence. One study found a 20 percent decrease in the incidences of severe injuries (e.g. broken bones, lacerations) due to domestic violence after decriminalization. The University of Pennsylvania analyzed statistics from 25 states from 2005 to 2016. The study confirmed that domestic violence rates didn’t change after legalization, but the level of injuries did.

Surprisingly, domestic violence cases involving a weapon decreased by 23.1 percent. Additionally, marijuana decriminalization was linked with a 40.7 percent decrease in domestic violence cases where alcohol was involved. Researchers believe marijuana acts as a substitute for alcohol.

Researchers cited that “given the evidence that alcohol is a substance which aggravates violence, the alcohol findings suggest both that (a) marijuana and alcohol are substitutes rather than complements, and (b) the substitutionary use of marijuana likely mitigates the severity of assaults.” Researchers also believe marijuana’s sedative properties make “would-be assailants sleepier” and therefore their assaults are less severe.

Correlation Does Not Imply Causation

Substance abuse has widely been believed to cause violent behaviors, but other factors should also be considered, including an individual’s personality and genetics. It’s difficult to assess causation when individuals are taking other harder substances that can induce paranoia and rage. Despite the limitations, some studies have shown that marijuana use, especially heavy use, is correlated with future violent behavior.

A 50-year study published in the journal Psychological Medicine studied 411 boys born around 1953 in London and found that 38 percent tried cannabis at least once in their life. 20 percent of the boys began using cannabis before they turned 18 and used it through middle age. One-fifth of weed users reported violent behavior after they began using cannabis compared to only 0.3 percent who reported violence before they started using cannabis.

The study concluded that “cannabis use predicts subsequent violent offending, suggesting a possible causal effect.” Unfortunately, the study was quick to blame pot for the violence when other confounding factors could have been at play, including family, peer, and community risk factors. Furthermore, researchers don’t account for the fact that violent offenders may be more likely to consume marijuana, a generally illegal substance at the time.

Mental Health and Violence

Devil’s advocates relish bringing up studies that show a link between marijuana use and psychiatric disorders such as psychosis (schizophrenia), depression, and anxiety, which they believe increases violence. The link, however, is affected by a variety of factors, which makes it hard to determine exactly how marijuana affects violent behavior. Some researchers have suggested that marijuana causes psychosis, while others state that those who are predisposed to psychosis are more likely to consume marijuana due to a genetic vulnerability.

For example, a 2018 study found that schizophrenia most likely leads to marijuana use as a self-medicating technique. Studies have shown that marijuana use was associated with violent behavior, but there are also other studies that contradict these findings. A review in 2013 commissioned by the Office of National Drug Control Policy found that “marijuana use does not induce violent crime, and the links between marijuana use and property crime are thin.”

While marijuana is known to cause acute paranoia and anxiety, education can help prevent harmful consumption. More often than not, however, marijuana is used to relieve many of the negative effects of psychiatric disorders, which can be caused by mental or physical trauma. In fact, many states have listed conditions like post-traumatic stress disorder (PTSD) as qualifying conditions for using medical marijuana.

Although marijuana use isn’t an effective predictor of future violent acts, there are many precautions that individuals should be taking before considering cannabis use. In some cases, cannabis use can worsen respiratory conditions or lead to dependence. Until we have more peer-reviewed longitudinal studies on the effects of marijuana use, we can’t demonize a plant that has been used for millennia. So we ask you, Does Marijuana Use Lead to Violent Behavior?