Large study finds link between cannabis use in teens and psychosis later
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[NPR](/) > [Health](/1128)A huge study finds a link between cannabis use in teens and psychosis later
By Rhitu Chatterjee
Saturday, February 21, 2026 · 7:44 AM EST
Heard on Weekend Edition Saturday
As marijuana use among teens has grown in the past decade, researchers have been trying to better understand the health risks of the drug. Now, a new longitudinal study finds that cannabis use among adolescents increases risks of being diagnosed with bipolar and psychotic disorders, as well as anxiety and depression, years later.
Related Story: NPR
“This is very, very, very worrying,” says psychiatrist Dr. Ryan Sultan at Columbia University, a cannabis researcher who wasn’t involved in the new study published in the latest JAMA Health Forum.
Strong study design
Researchers analyzed health data on 460,000 teenagers in the Kaiser Permanente Health System in Northern California. The teens were followed until they were 25 years old. The data included annual screenings for substance use and any mental‑health diagnoses from the health records. Researchers excluded adolescents who had symptoms of mental illness before using cannabis.
“We looked at kids using cannabis before they had any evidence of these psychiatric conditions and then followed them to understand if they were more likely or less likely to develop them,” says Dr. Lynn Silver, a pediatrician and researcher at the Public Health Institute and an author of the new study.
Key findings:
- Teens who reported using cannabis in the past year were at a higher risk of being diagnosed with several mental‑health conditions a few years later, compared with teens who didn’t use cannabis.
- Those teens had twice the risk of developing two serious mental illnesses:
- Bipolar disorder (alternating episodes of depression and mania)
- Psychotic disorders such as schizophrenia (a break with reality)
Only a small fraction—nearly 4,000 of all teens in the study—were diagnosed with each of these two disorders, but both are among the most serious and disabling mental illnesses.
“Those are the scarier conditions that we worry about,” says Sultan.
Silver notes that these illnesses are expensive to treat and impose a high cost on society. While the U.S. cannabis market is valued in the tens of billions of dollars, the societal cost of schizophrenia has been estimated at $350 billion a year.
“If we increase the number of people who develop that condition in a way that’s preventable, it can wipe out the whole value of the cannabis market,” Silver says.
Depression and anxiety, too
The study also found higher risks for more common conditions:
- Depression increased by about one‑third.
- Anxiety increased by about one‑quarter.
The link between cannabis use and these conditions was weaker for teens who were older when they used cannabis, underscoring the sensitivity of the younger brain to cannabis’s effects.
“The brain is still developing. The effects of cannabis on the receptors in the brain seem to have a significant impact on neurological development and the risk for these mental‑health disorders,” Silver explains.
Silver hopes the findings will make teens more cautious about using the drug, which is not as safe as many perceive.
“With legalization, we’ve had a tremendous wave of the perception of cannabis as a safe, natural product to treat stress. That is simply not true.”
The study’s design helps answer the classic “chicken‑or‑egg” question. Earlier research found associations between cannabis use and mental‑health conditions but could not determine causality because they did not exclude participants with pre‑existing symptoms. By excluding teens who already showed mental‑health symptoms, this study points to a potential causal link between cannabis use and later diagnoses. Additional research is needed to fully understand the relationship.
“Playing with fire”
Sultan, the psychiatrist and researcher at Columbia University, says the study confirms what he’s seeing in his clinic—more teens using cannabis are developing new or worsening mental‑health symptoms.
“It is most common around anxiety and depression, but it’s also showing up in more severe conditions like bipolar disorder and psychosis,” he says.
Related Story: NPR
He notes that mental‑health disorders are complex in origin, with genetics, environment, lifestyle, and life experiences all playing a role. Some young people are more at risk than others.
“When someone has a psychotic episode in the context of cannabis—or a manic episode in the context of cannabis—clinicians are going to say, ‘Please do not do that again because you’re playing with fire,’” he says.
Because the more they use the drug, the more likely their symptoms will worsen over time, making recovery harder.
“What we’re worried about is that if you get stuck in psychosis, it gets harder and harder to pull the person back,” Sultan adds.
Transcript
SCOTT SIMON, HOST:
Marijuana use among teens has grown in the past decade, and researchers have been trying to better understand the health risks. Now a new study finds that cannabis use among teens increases risks of being diagnosed with bipolar and psychotic disorder years later. NPR’s Rhitu Chatterjee has more.
RHITU CHATTERJEE, BYLINE:
Researchers analyzed health data on nearly half a million teenagers in the Kaiser Permanente health system in Northern California. The data included annual screenings for substance use and any mental‑health diagnoses all the way until they were young adults. Pediatrician Dr. Lynn Silver at the Public Health Institute in California is one of the authors of the study.
LYNN SILVER:
We looked at kids using cannabis before they had any evidence of these psychiatric conditions and then followed them to understand if they were more likely or less likely to develop them.
CHATTERJEE:
They found that the teens who reported using cannabis in the past year were at a higher risk of being diagnosed with several mental‑health conditions a few years later, compared to teens who didn’t use cannabis.
SILVER:
What we found is extremely worrisome.
CHATTERJEE:
The highest risk was for two disorders—bipolar, which manifests as alternating symptoms of depression and mania, and psychotic disorders.
SILVER:
And psychotic disorders means ones where you hear or see things that aren’t real. Typically, it can be anything from an episode to actual schizophrenia.
CHATTERJEE:
Now, only a small percentage—about 1 % of the teens—were diagnosed with these two disorders, but the risk of developing them doubled for teens who used cannabis versus those who didn’t. Silver notes that both bipolar and psychotic disorders are among the most serious and disabling of mental illnesses. The risk for more common conditions, like depression and anxiety, was also higher among cannabis users. Silver hopes that the study published in JAMA Health Forum will make teens more cautious about using the drug, which is not as safe as they think it is.
SILVER:
With legalization, we’ve had a tremendous wave of misperception of cannabis as a safe, natural product to treat your stress with.
CHATTERJEE:
Psychiatrist Dr. Ryan Sultan at Columbia University also researches the impacts of cannabis use on teens but wasn’t involved in the new study. He finds the results worrying, and it confirms what he’s seeing in his clinic—more teens using cannabis who have developed new or worsening mental‑health symptoms.
RYAN SULTAN:
It is most common around anxiety and depression, but it’s also showing up in more severe conditions like bipolar disorder and psychosis.
CHATTERJEE:
He notes that mental‑health disorders are complex in origin. A host of risk factors—genetics, environment, lifestyle, and life experiences—all play a role, and some young people are more at risk than others.
SULTAN:
Which is why, when someone has a psychotic episode in the context of cannabis or a manic episode in the context of cannabis, you know, clinicians are going to say, “please do not do that again because you’re playing with fire.”
CHATTERJEE:
Because the more they use the drug, he says, the more likely their symptoms will worsen over time, making recovery harder.
Rhitu Chatterjee, NPR News.
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