Is Marijuana a Safe Drug? Teenage Brain at Risk for Drug Abuse

Marijuana isn't a "safe" drug--at least not for the teenage brain. Scientists have discovered that the nature of the teenage brain makes users of cannabis among this population particularly at risk of developing addictive behaviors and suffering other long-term negative effects.

In order to examine the effect of cannabis on the adolescent brain, the researchers reviewed over 120 studies that looked at different aspects of the relationship of the drug with the teenage brain.  This included the biology of the brain, chemical reaction that occurs in the brain when the drug is used and the influence of genetics and environmental factors.

"Data from epidemiological studies have repeatedly shown an association between cannabis use and subsequent addiction to heavy drugs and psychosis (i.e. schizophrenia)," said Didier Jutras-Aswad, one of the researchers, in a news release. "Interestingly, the risk to develop such disorders after cannabis exposure is not the same for all individuals and is correlated with genetic factors, the intensity of cannabis use and the age at which it occurs. When the first exposure occurs in younger versus older adolescents, the impact of cannabis seems to be worse in regard to many outcomes such as mental health, education attainment, delinquency and ability to conform to adult role."

Currently, it's difficult to confirm a certain causal link between drug consumption at the resulting behavior. Though the researchers did point out that rat models allow scientists to explore and directly observe the same chemical reactions that occur in the human brain. More specifically, it allows scientists to watch how cannabis interactions through chemical receptors (namely CB1 and CB2). These receptors are situated in the areas of our brain that govern learning and management of rewards, motivated behavior, decision-making, habit formation and motor function. Since the structure of the brain changes rapidly during adolescence, it's possible that the consumption of cannabis during this time could influence the way in which these sections develop.

So what else did the researchers find? Only a minority (about one in four) of teenage users will develop an abusive or dependent relationship with the drug. This points to the fact that specific genetic or behavioral factors influence the likelihood that drug use will continue.

Currently, a lot still remains unknown about the mechanics of cannabis use. Yet this study does show that more research needs to be conducted.

"It is now clear from the scientific data that cannabis is not harmless to the adolescent brain, specifically those who are most vulnerable from a genetic or psychological standpoint," said Jutras-Aswad.

The findings are published in the journal Neuropharmacology.