Teen Marijuana Use and ADHD: What to Know

Medically Reviewed by Dan Brennan, MD on May 23, 2022
5 min read

Teenage “rebellion,” like trying marijuana or cannabis, is a typical part of growing up. Recent data showed that 4 in 10 high school students have tried marijuana at some point. Twenty-two percent used the drug within 30 days of the survey.

Engaging in these types of activities is even more common for teens with ADHD. One study found that teens with ADHD are three times more likely than other teens to use marijuana. They also had a 50% increase in risk for a cannabis use disorder.

There may be lots of reasons that teens with ADHD might use marijuana more often than other teens. These include:

  • Teens with ADHD are more prone to risky or impulsive behavior.
  • Teens with ADHD may struggle in school or with friends.
  • They may think it will help with ADHD or symptoms such as anxiety.
  • Teens with ADHD may be more likely than other teens to have parents who use substances, including marijuana.
  • ADHD and substance use disorders may have some genetic factors in common.

The human brain continues to grow and change until around age 25. So there’s reason for concern that substance use in teen years could do lasting harm to the brains of young people, whether they have ADHD or not.

Marijuana in teens is linked to:

  • Trouble thinking or solving problems
  • Trouble remembering things or learning
  • Worse coordination
  • Trouble paying attention
  • Trouble at school or with friends

Teens with ADHD may already struggle in these areas, so it’s possible that marijuana could make symptoms and signs of ADHD worse. For teens with ADHD, the effects of marijuana may also lead to problems such as:

  • Car accidents
  • Changes in brain development
  • Not doing well in school or dropping out
  • Feeling unsatisfied in life
  • Chronic bronchitis or other respiratory symptoms
  • More risk for other mental health disorders including psychosis

Some studies have looked at what happens when young people with ADHD use marijuana or cannabis and the results are somewhat mixed. For example, one 2016 study looked at how marijuana use affects changes in the brain related to ADHD. They looked at 74 adults in their early 20s who had been diagnosed with ADHD as kids. Some of them were frequent marijuana users and others didn’t use marijuana.

The researchers looked at how the brain was working in the different groups. They thought they might find that marijuana made changes seen in ADHD brains worse. But they didn’t see that. They saw changes you’d expect in ADHD. But it didn’t look like marijuana had made those any worse. The researchers said that more research is needed to understand what happens in the brains of young people with ADHD who use marijuana.

Another 2016 study that looked at the brains of young adults found something similar. People with ADHD have more trouble with distractions than those without ADHD. Scientists wanted to know how marijuana use would affect this. In the study, those with ADHD made more errors while completing the assigned task. But marijuana use didn’t seem to have any effect. So it wasn’t clear in the study that using marijuana had made signs and symptoms of ADHD any worse.

More recently, researchers reviewed studies that looked at the effects of marijuana on brain structure, function, and other outcomes in teens and young adults with ADHD. They found 11 studies that looked at this. Most of the studies used brain imaging. None of the studies showed that marijuana made study participants with ADHD do worse on tasks. Two studies did suggest there were negative effects of using marijuana at a young age.

Overall the researchers concluded that there’s not enough evidence on how marijuana use affects the developing brain or brain function in young people with ADHD. They suggest that more research is needed given that teens with ADHD are at higher risk for using marijuana and other substances.

Another recent study looked at 62 young people just emerging from the teen years into adulthood. They wanted to look at why people with ADHD use marijuana, including coping, boredom, and sleep and see how that related to ADHD symptoms. They found that the consequences of using marijuana were greater for people who also reported worse ADHD symptoms in the last 6 months. The findings suggest that marijuana might have made ADHD symptoms worse.

There’s no evidence that marijuana helps teens with ADHD with their symptoms or otherwise. There’s also reason to think that it might make some ADHD symptoms worse. But you can find discussions online that suggest marijuana might be good for ADHD. So one reason teens with ADHD might use it is because they think based on things they read or hear that it might help.

One study looked at how the effects of marijuana in ADHD are talked about online. Researchers found more than 250 different threads on various online forums. They analyzed a random sample to see what people were saying.

It turned out many of them – 1 in 4 – talked about marijuana’s benefits for ADHD. Only 8% said it was harmful. Others said it had benefits and harms or no effect. So even though there are reasons to think marijuana use isn’t a good idea when teens have ADHD, it’s easy to find information suggesting the opposite.

Given how common it is for teens to use or at least try marijuana, it’s a good idea to talk to them about it early. They might hear it called other things like cannabis, pot, or weed. They might see other teens using marijuana in different ways. It can be smoked, vaped, or eaten in baked goods or candies. Your teen should know that it isn’t legal for minors to use marijuana, even in states where adults can. If your teen has ADHD, talk to them about what’s known about the risks that marijuana might have for them.

Experts offer these tips for talking to teens about marijuana:

  • Ask them what they know and listen to what they say. Don’t interrupt or get angry.
  • Give them information about the risks and what could happen if they use marijuana.
  • Ask questions and discuss it so that you are sure they understand.
  • It’s OK to be honest about your own experiences if you choose to, but keep in mind that marijuana is stronger now than it used to be and the risks may be greater for your teen with ADHD.

If you suspect or know your teen with ADHD is using marijuana, experts say you shouldn’t ignore it. Let your child know what it might mean for their ADHD symptoms on top of the general risks. You can’t control what they’ll do, so some experts say it may help more to let them know you care and help them understand the risks for themselves.