Marijuana use among high school students is significantly lower today than it was 15 years ago, despite wider availability in many parts of the country, according to a new study by researchers at the Johns Hopkins Bloomberg School of Public Health.
Marijuana policy has undergone significant changes during the last two decades. Since 1996, 34 states have passed laws that allow the medical use of marijuana. Eleven states have passed laws decriminalizing possession of small amounts of marijuana, adding to nine that passed such laws in the late 1970s. Four states have passed laws allowing for the recreational use of marijuana for people over 21.
“People have been very quick to say that marijuana use is going up and up and up in this country, particularly now that marijuana has become more normalized,” said study leader Renee M. Johnson, Ph.D., M.P.H., an assistant professor in the Department of Mental Health at the Bloomberg School.
“What we are seeing is that since 1999, three years after medical marijuana was first approved, the rates of marijuana use have actually fallen. But we will be watching those states where recreational marijuana use has been legalized to see if that leads to increased use among teens.”
Johnson says she isn’t sure why rates of marijuana use have fallen since 1999. The 1980s and the early 1990s were a time when it was very difficult to obtain marijuana due to a federal crackdown on illicit drugs and strong anti-drug education programs, such as the “just say no” campaign. But use shot back up in the late 1990s.
While rates of use have been falling since 1999, they started to rise again in 2009. Time will tell, she says, whether the recent uptick in marijuana use is just a statistical blip or a sign that greater availability of the drug is leading to a reversal of the decade-long downward trend.
Colorado, Oregon, Alaska, Washington, and the District of Columbia have passed laws recently that legalize some recreational use of marijuana. The longer those laws are in place, Johnson says, the more likely there could be an effect on marijuana use among teens¬†— even though it is technically illegal to use pot under age 21.
Marijuana use is still significantly greater than the use of other illegal drugs with 40 percent of teens in 2013 saying they have smoked marijuana. That number was down from 47 percent in 1999 but up from 37 percent in 2009. By contrast, just three percent had ever tried methamphetamines in 2013 as compared to nine percent in 1999.
The study also suggests that the gender gap in marijuana use, where boys outnumbered girls as users of the drug, is shrinking, with males and females now using marijuana at similar rates. And while white and black teens once used marijuana at similar rates, now blacks report using the drug more often.
Overall, the survey found that in 1999, 51 percent of boys and 43 percent of girls had ever used marijuana, and by 2013, 42 percent of boys and 39 of girls say they had used it in their lifetimes. In 1999, 29 percent of both white and black teens reported having used marijuana; whereas in 2013, 29 percent of black teens and 20 percent of white teens had used the drug.
The findings are published online in the journal Drug and Alcohol Dependence.