Marijuana use increases violent behaviour, suggests study

Marijuana is considered to be a medicinal drug and if consumed for health purposes, it can be useful for a person.

But if taken in great quantity it can adversely affect your mental health, and now after long debates and discussions, a new study has found a link between use of marijuana and changes in brain function.

A group of researchers has found that continued use of cannabis causes violent behavior as a direct result of changes in brain function that are caused by smoking weed over many years.

The study which studied 1,136 patients with mental illnesses who had been seen five times during the year after discharge, took into account substance use and the onset of violent behaviour.

A previous research has already shown that a cannabis use disorder is associated with violent behaviour. But according to this new study, users who reported at each follow-up visit that they continued to smoke cannabis presented an increased risk (+144 percent) of violent behaviour.

These results also confirm role of chronic cannabis use in patients with mental illness.

"An interesting feature of our results is that the association between persistent cannabis use and violence is stronger than that associated with alcohol or cocaine," noted principal researcher Alexandre Dumais.

Persistent cannabis use should therefore be considered as an indicator of future violent behaviour in patients who leave a psychiatric hospital for follow-up in an outpatient clinic, although the researcher points out that this behaviour tends to fade with time.

Dr. Dumais added, "This decrease could be explained by better adherence to treatment (the patient becomes more involved in their treatment over time) and by better support from their entourage. Even though we observed that violent behaviour tended to decrease during follow-up periods, the association remained statistically significant."

The results also shows there is no reciprocal relationship, that is, the use of cannabis resulted in future violent behaviour and not the reverse

A recent meta-analysis of neuroimaging studies demonstrated that chronic cannabis users have deficits in the prefrontal cortex, a part of the brain that inhibits impulsive behaviour.

These results are important because they offer additional information to young adults, who can evaluate the risks of cannabis before deciding whether or not to use it.

The study was published in journal Frontiers in Psychiatry.