Does Medical Marijuana Legalization Impact Teen Drug Use?

By Kelly Burch 02/27/18

Researchers have conducted yet another study attempting to prove once and for all that medical marijuana legalization doesn't increase teen use.

person passing a joint to another person

Despite studies that indicated that the legalization of medical marijuana does not increase pot use among teens, skeptics and opponents of marijuana legalization continued to question whether that could really be the case.

This prompted researchers to do a thorough review of all the reliable studies that concluded that medical marijuana legalization does not impact teen cannabis use. 

“We had done an earlier study published in the Lancet in 2015 of a million adolescents that were surveyed yearly between 1991 and 2014, and found no increase in teen use of cannabis or marijuana. We were surprised by that result,” Dr. Deborah S. Hasin, a study author and professor of epidemiology at Columbia University, told ABC News

Despite the wide-reaching data set for that survey, some still refused to believe that teen drug use did not increase after medical marijuana was legalized. “People were so convinced that medical marijuana laws were going to increase teen use so they questioned the relationship,” Hasin said. 

To get a more comprehensive picture, researchers examined 11 studies of teen marijuana use in states that had legalized medical pot. The studies covered data from more than two decades, from 1991 to 2014. However, none of them found any link between the legalization of medical marijuana and increasing teen pot use. 

Hasin was confident that the studies present the full picture. “Altogether, if there was any weak relationship, it would have been found,” Hasin said. “But there was no evidence for increased recreational marijuana use post medical marijuana legalization in teens.”

However, there does remain a big unknown as more states allow adult use (or "recreational use") of cannabis. “What we really don’t know about is [the effects of] recreational marijuana laws,” Hasin said.

Studies have been done in Washington and Colorado, the first states to legalize cannabis for adult use. In Washington, researchers found an increase in teen use, but in Colorado there was no increase. 

Proponents of marijuana legalization point out that teens already have access to pot under current laws that prohibit marijuana. 

Dr. M-J Milloy, a research scientist with the British Columbia Centre on Substance Use, said that if most sales of marijuana were happening on the legal market, underage people might have a harder time getting the drug. 

“With the current prohibition scheme, teens are still able to access it,” said Milloy. “Hopefully, by forming a public health regulated system—stores that check IDs instead of dealers who do not—we may see a decline in teen use.”

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Kelly Burch writes about addiction and mental health issues, particularly as they affect families. Follow her on TwitterFacebook, and LinkedIn.