Legal medical pot doesn't lead to increased use in teens, research shows

With medical marijuana already legal in 29 states and even more states considering legalization, some believe that the inevitable next step is an increase in recreational marijuana use among adolescents, but a new study published today in Addiction busted that myth.

Marcus Yam/Los Angeles Times via Getty Images

Marcus Yam/Los Angeles Times via Getty Images

“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,” said Dr. Deborah S. Hasin, an author of the study and professor of epidemiology at Columbia University.

But despite a series of similar studies with the same result, she said, “People were so convinced that medical marijuana laws were going to increase teen use so they questioned the relationship.”

In order to provide a more definite answer, the study authors went back to do a meta-analysis, a look at all the past studies that were rigorous enough to be included. They systematically reviewed 2,999 academic papers to find 11 suitable studies to pool together.

None of the 11 studies, which covered data from 1991 to 2014, found an increase in past-month marijuana use among teens after medical marijuana was legalized in their state.

“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, this study does not mean that teens are unaffected by any type of marijuana legalization.

“Regular marijuana use in teens has been shown to lead to impairments in neurodevelopment, later academic functioning, and occupational achievement. Rightly so, people are concerned about teen use -- whether that’s with medical marijuana legalization or not,” Hasin said. “What we really don’t know about is [the effects of] recreational marijuana laws.”


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PhotoAlto/Katarina Sundelin/PhotoAlto/Getty Images

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