Researchers at the University of Montreal and New York's Icahn School of Medicine at Mount Sinai have found that teenagers using marijuana are at an increased risk of developing addiction to the drug.

Marijuana is a highly popular and easily accessible drug. About 48 percent ofl people in the U.S. have used the drug. Recent estimates from Centers for Disease Control and Prevention reported that more teens are smoking marijuana than cigarettes. Related studies have shown that teens know tobacco causes severe health damage, but believe that marijuana use is less risky.

About 6.5 percent of all high school students smoke marijuana daily, according to another survey by University of Michigan.

"Of the illicit drugs, cannabis is most used by teenagers since it is perceived by many to be of little harm. This perception has led to a growing number of states approving its legalization and increased accessibility. Most of the debates and ensuing policies regarding cannabis were done without consideration of its impact on one of the most vulnerable population, namely teens, or without consideration of scientific data," wrote Professor Didier Jutras-Aswad of the University of Montreal and Yasmin Hurd, MD, PhD, of Mount Sinai.

Researchers looked at data from over 120 studies that were conducted on cannabis and its effects on teenage brains. The studies assessed various aspects of marijuana use including the drug's effects on the biology of the brain, the chemical reaction, genetic and environmental factors that encourage addiction to the drug and even its potential as a gateway drug.

According to the researchers, it is difficult to draw a cause-effect relationship between marijuana use and resulting behavior. However, studies in rat models have shown that cannabis interacts with receptors in the region of the brain that is associated with decision-making and learning.  During teenage years, the brain undergoes significant changes and using marijuana at this age leads to major changes in personality and behavior.

About a quarter of all teens using marijuana will go on to have a full-blown addiction to the drug.

Researchers added that although more research is required to understand the effects of marijuana use, the existing literature supports the idea that marijuana use damages teenagers' brains.

"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. Identifying these vulnerable adolescents, including through genetic or psychological screening, may be critical for prevention and early intervention of addiction and psychiatric disorders related to cannabis use. The objective is not to fuel the debate about whether cannabis is good or bad, but instead to identify those individuals who might most suffer from its deleterious effects and provide adequate measures to prevent this risk" Jutras-Aswad said in a news release.