By Andrea Petersen

Legalization of recreational marijuana by many states has made it easier for teens to get access to highly potent and convenient forms of the drug, creating new hazards for teen health.

New research shows that using it as little as once a month or less as a teenager is linked to an increased risk of developing psychiatric disorders and doing poorly in school.

Of the more than 460,000 teens ages 13 to 17 who researchers asked about cannabis use, the ones who said they had used it in the prior year had a higher likelihood of developing depression and anxiety disorders, according to a study published last month in the journal JAMA Health Forum.

"We can't find a level of cannabis use in a teenager that we don't see a negative effect," said Dr. Ryan Sultan, assistant professor of clinical psychiatry at Columbia University Irving Medical Center who treats patients with cannabis use disorder.

The new concerns about the impact of marijuana on kids' health is one of the factors driving a crackdown on the use of the drug at schools.

Here's what the science says about cannabis and teens:

Mental health and addiction

The teenage brain is especially vulnerable to cannabis because it is still developing. THC, the main psychoactive component of cannabis, can alter the development of systems in the brain involved in decision-making, emotion regulation and reward processing.

Studies bear that out. Young people who said they used cannabis during the prior year had a higher risk of developing psychosis or bipolar disorder when compared with those who said they hadn't used the drug, according to the JAMA Health Forum study.

Teens are also particularly vulnerable to addiction. Starting to use cannabis before age 18 significantly increases the risk of developing cannabis use disorder, said Dr. Jonathan Avery, vice chair for addiction psychiatry at Weill Cornell Medicine. The disorder is characterized by craving the drug and being unable to cut down on use.

Avery said he has seen teen patients develop an addiction in as little as a few weeks. "Innocent kids get a vape for the first time. Then they try to stop and they feel really bad and they're like, 'Whoa, I need this,' " he said. Withdrawal symptoms include difficulty sleeping, anxiety and depression.

Until the early 2000s, cannabis flower, the part of the plant typically rolled into a joint and smoked, contained about 3% to 5% THC, said Jodi M. Gilman, director of neuroscience at the Center for Addiction Medicine at Massachusetts General Hospital. Now, many cannabis shops sell products that can contain as much as 90% THC.

These higher-potency drugs present bigger risks for teens. The forms popular today, like vapes and edibles, make it easy for kids to use -- and hide -- high-potency marijuana.

In the 24 states and Washington, D.C., where recreational marijuana is legal, buyers are required to be age 21 or over. But teens say it is easy to get marijuana from older siblings, friends and acquaintances.

Learning and memory issues

Regularly using cannabis during adolescence is associated with disruption in memory and learning, according to several studies. Gilman and her colleagues have shown in their research that people who begin using cannabis weekly or multiple times a week before age 16 perform poorly on tasks that require retaining new information.

Other research has shown that frequent cannabis users who began using it in adolescence lost several IQ points between the ages of 13 and 38.

Even low-level use in adolescence is associated with poorer academic performance, new research has found. Teens who used cannabis monthly or less were more likely to have a low grade-point average, not participate in extracurricular activities and not have plans for college compared with those who didn't use cannabis in the prior year, according to a recent study in the journal Pediatrics by Sultan and colleagues. They also were more likely to get into fights.

The message for teens and parents is to delay marijuana use as long as possible, ideally until age 25 when brain development is largely complete, says Staci Gruber, director of the Marijuana Investigations for Neuroscientific Discovery $(MIND)$ program at McLean Hospital in Massachusetts.

"If you can make it through high school, make it through college," Avery said, "the later onset is really protective."

Write to Andrea Petersen at andrea.petersen@wsj.com

(END) Dow Jones Newswires

March 14, 2026 12:00 ET (16:00 GMT)

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