Contrary to often-expressed fears of marijuana legalization opponents, teens living in states that allow medical cannabis are actually less likely to use the drug compared with those in non-legal states.
That's the result of a new study published in The American Journal of Drug and Alcohol Abuse.
Researchers at Boston College looked at national youth drug surveys from 1999 to 2015 — a data set that involved more than 860,000 adolescents across the United States. They investigated how self-reported marijuana use changed in states that have either decriminalized cannabis possession or legalized it for medical purposes.
And while opponents of legalization have long argued that loosening marijuana laws would drive more youths to consume cannabis, the study showed the opposite. The enactment of medical cannabis laws was associated with 1.1 percentage point reduction in marijuana use among teens.
“We found that for every group of 100 adolescents, one fewer will be a current user of marijuana following the enactment of medical marijuana laws,” study author Rebekah Levine Coley said in a press release.
That decline was even more pronounced within certain subgroups. For example, 3.9 percent fewer black adolescents and 2.7 percent fewer Hispanic adolescents used marijuana in legal medical cannabis states.
The trend also held true after researchers accounted for factors such as state demographics and economic trends. What's more, the reductions in youth marijuana use were more significant the longer a state had a medical cannabis system in effect.
“Some people have argued that decriminalizing or legalizing medical marijuana could increase cannabis use amongst young people, either by making it easier for them to access, or by making it seem less harmful,” Coley said. “However, we saw the opposite effect.”
“We were not able to determine why this is, but other research has suggested that after the enactment of medical marijuana laws, youths' perceptions of the potential harm of marijuana use actually increased. Alternatively, another theory is that as marijuana laws are becoming more lenient, parents may be increasing their supervision of their children, or changing how they talk to them about drug use.”
States that have simply decriminalized cannabis possession did not experience the same reductions in youth marijuana use, the study also found. There were slight declines in usage among 14-year-olds and Hispanic youths, but the broader reductions were only seen in medical marijuana states.