Study: Marijuana Makes People Less Aggressive

Craig Boudreau


A new study, fittingly done by the Netherlands and published in the journal Psychopharmacology, says that alcohol increases aggressive tendencies, while marijuana decreases them.

The team of researchers selected 20 people to drink alcohol, 21 to smoke marijuana, and 20 controls who used neither of the substances. They then put the people in situations that would presumably elevate levels of aggression. Researchers asked the individuals to rate their level of aggression on a 100 point scale, both before and after going through the tests. They also measured testosterone and cortisol levels in the people after the tests were administered as a ‘secondary outcome measure’.

The team found that there was no difference in aggressive responses for any of the three groups while sober. But the alcohol group displayed increased aggression while under the influence as compared to the control group, while the marijuana group displayed lower levels of aggression than the control group. The findings were republished in The Washington Post Wednesday.

“It is concluded that alcohol facilitates feelings of aggression whereas cannabis diminishes aggressive feelings in heavy alcohol and regular cannabis users, respectively,” the study reads.

While the findings show a definite decrease in aggressive tendencies while under the influence of marijuana, another study published in the journal Psychopharmacology in 1999 found that during the withdrawal phase of marijuana, aggression levels spike.

“Our findings confirm previous reports of an abstinence syndrome associated with chronic marijuana use and suggest that aggressive behavior should be an additional component of this syndrome,” lead author, Elena M. Kouri, wrote in the abstract.

The study refers to another study done in 1978, which showed that animals who had ingested THC had shown a decreased levels of aggression “[THC] decreased species-specific attack behavior in mice, rats, and squirrel monkeys at doses,” the abstract reads.

They also refer to a study published in Psychopharmacology in 1992, which linked marijuana use to aggression, but this latest study says there were serious flaws with the 1992 study. The researchers say the 1992 study used a small sample size and only included “male participants with self-reported anti-social tendencies.”
 

In what appears to be a common sense conclusion, the study also said that aggression levels tend to increase as the amount of alcohol in their system increases. However, the study did not find the same to be true with increased levels of THC (the active ingredient in marijuana) in their systems.

 “The results in the present study support the hypothesis that acute alcohol intoxication increases feelings of aggression and that acute cannabis intoxication reduces feelings of aggression following aggression exposure,” the study concludes.

Further corroborating the studies findings, a 2014 study by the University of Buffalo found that marijuana use among married couples showed decreased incidences of domestic violence, as reported by The Washington Post.