Does Legalizing Cannabis Increase Adolescent Use? This Expert Found Mixed Results.

Contrary to expectation, a major study found that weed use among minors was lower in states where the drug was legal.

With weed these days, it’s a Willy Wonka world: chocolate bars, lollipops, exotic-flavored gummies — to say nothing of joints, vapes, drinks and the rest. Twenty-four states and the District of Columbia have now legalized the sale of marijuana for recreational use, prompting innovation, lowering prices and making the drug — more potent than ever — more widely available. The Biden administration this week recommended easing the federal regulations on cannabis.

What does all of this mean for adolescents?

Studies have demonstrated that marijuana use can harm the developing brain. Some new strains have been linked to psychosis. Many health experts have worried that relaxing the laws around cannabis will lead to more use of the drug among minors. But Rebekah Levine Coley, a developmental psychologist at Boston College, is less certain.

In April, she and colleagues published a study in JAMA that examined drug use patterns among 900,000 high school students from 2011 to 2021, using self-reported data from the Youth Risk Behavior Survey. They found that fewer minors reported having used cannabis in the previous month in states where the drug had been legalized. But they also found that in the 18 states that had both legalized cannabis and allowed retail sales of the drug, some adolescents who were users of the drug used it more frequently. The net effect was a flat or slight decline in cannabis use among adolescents.

Dr. Coley spoke to The New York Times about the study, and its implications for state and federal drug policy. This conversation has been edited and condensed for clarity.

It seems sensible to assume that legalizing marijuana would lead to more use by young people.

Yes, common sense might argue that as cannabis becomes legalized, it will be more accessible. There will be fewer potential legal repercussions, hence availability would increase and use would increase.

We did not find that with adolescents. If anything, we are seeing very small declines in cannabis use in states that legalized recreational cannabis, as well as declines in alcohol use and e-cigarettes.

What’s the connection to those substances?

There are different theories. Some argue that individuals often use substances together. So if you increase the use of one substance, you’re likely to increase the use of other substances. Similarly, if you decrease one substance, you may decrease other substances as well.

Why would marijuana use go down as the drug has been legalized?

One possible explanation is that moving cannabis from the illegal market and street sales into the legal marketplace, where access is restricted for people under 21, has actually lowered access for adolescents.

Another theory is that as cannabis has become legalized, parents and others are more aware of potential access for their children, and that parents are having more discussions with adolescents about the potential risks or imposing more supervision.

Alcohol was legal in prior generations, and parents were aware, yet binge drinking soared in the 1980s and 1990s. How is the current situation different?

There are different types of awareness. Some of the public-health campaigns about the danger of cigarettes and the severe health implications of tobacco use have definitely had an effect in lowering use, particularly among young people, and stopping people from starting cigarette use in the first place. We also have seen some success in slowing an extremely rapid rise in e-cigarettes.

It’s also important to point out that substance use overall has decreased quite notably among adolescents.

Another idea is that there is a growing norm among adolescents toward overachievement and control and against hedonism, and much less time with peers. But these explanations can help to explain overall trends in adolescent risk behaviors and substance use. They do not explain the state-to-state differences that we found, in which legalization of recreational cannabis was linked with lowering substance use.

You did find some trends that conflicted. Can you explain?

We found that after states enacted legal commercial sales of cannabis for adults aged 21 and above, the number of adolescents reporting no cannabis use in the previous month increased. At the same time, among adolescents who were users, their frequency of use increased. That’s a problem because early and heavy use of cannabis is particularly concerning.

Is there some other commonality among the states that legalized cannabis that might explain the patterns in adolescent use?

That’s possible. We do adjust for many state characteristics, like unemployment rates and other substance-use policies that may indicate a more liberal or conservative state culture and policy context overall. But that still doesn’t allow us to definitely prove that cause and effect — that is, whether legalization is causing changes in youth substance use.

You’re showing correlation.

Right. Cause and effect remains an open question.

How do these results affect how you think about policy changes that might relax cannabis laws at the federal level?

The evidence provides some hope that increasing legalization, even at a federal level, will not lead to substantial increases in adolescent use. That said, we know that there are some notable potential health implications of adolescent use of cannabis. For example, vaping and the consumption of edibles are particularly attractive to teens and also are harder to dose, and there is strong evidence that earlier entry into substance use is linked to a higher likelihood of abuse and dependence. So continuing to track adolescent use of cannabis and other substances remains a key public health concern.

The New York Times 22.5.2024