Sparse evidence for cannabis to treat mental health conditions highlights research gap

## Summary
Health Sparse evidence for cannabis to treat mental health conditions highlights research gap March 17, 2026 12:57 PM ET By Will Stone Many say they use cannabis for their mental health, but there's no evidence it helps Listen · 3:09 3:09 Transcript Toggle more options Download Embed Embed < iframe src="https://www.npr.org/player/embed/nx-s1-5750489/nx-s1-9690891" width="100%" height="290" frameborder="0" scrolling="no" title="NPR embedded audio player"> Transcript While many people turn to cannabis to help with mental health conditions, the scientific evidence is scant. Treatments Cannabis blunts back pain in 2 new studies The findings, published in the medical journal The Lancet Psychiatry, underscore the extent to which the public's embrace of cannabis has outpaced the scientific research. Insomnia, autism and tic or Tourette's syndrome had more supporting data, though even that evidence was deemed "low quality" by the authors. "We clearly need to do more research on cannabis medicines," says Jack Wilson , a postdoctoral research fellow at the Matilda Centre for Research in Mental Health and Substance Use at the University of Sydney who led the review. "In the absence of evidence at this time, the routine use of medical cannabis products really should be rarely justified for the treatment of mental health disorders," he told NPR. And some patients try it and things get worse." cannabis medical marijuana mental health medical research Facebook Flipboard Email

## Article Content
Health
Sparse evidence for cannabis to treat mental health conditions highlights research gap
March 17, 2026
12:57 PM ET
By
Will Stone
Many say they use cannabis for their mental health, but there's no evidence it helps
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While many people turn to cannabis to help with mental health conditions, the scientific evidence is scant.
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Justin Sullivan/Getty Images
Along with chronic pain, mental health conditions are some of the top reasons people use marijuana for medical purposes.
But a
sweeping review
of cannabis studies over the past 45 years concludes there is little to no high-quality evidence showing this is effective.
Treatments
Cannabis blunts back pain in 2 new studies
The findings, published in the medical journal
The Lancet Psychiatry,
underscore the extent to which the public's embrace of cannabis has outpaced the scientific research.
The new analysis represents the largest effort yet to systematically parse all the data from randomized-controlled trials on cannabis and mental health. A team of researchers in Australia looked at more than 50 clinical trials, considering a wide range of conditions, formulations and types of cannabinoids.
The analysis turned up no evidence that cannabis can help with symptoms of anxiety, post-traumatic stress disorder or depression — the psychiatric conditions that medical marijuana users
most often mention
when asked why they're taking the drug.
Insomnia, autism and tic or Tourette's syndrome had more supporting data, though even that evidence was deemed "low quality" by the authors.
"We clearly need to do more research on cannabis medicines," says
Jack Wilson
, a postdoctoral research fellow at the Matilda Centre for Research in Mental Health and Substance Use at the University of Sydney who led the review. "In the absence of evidence at this time, the routine use of medical cannabis products really should be rarely justified for the treatment of mental health disorders," he told NPR.
National
Marijuana rescheduling would bring some immediate changes, but others will take time
The findings are not altogether surprising for cannabis researchers who know first-hand
how challenging
it is to conduct and fund well-controlled trials. For more than 50 years, cannabis has been listed as
Schedule 1 drug
by the Drug Enforcement Administration, though President Trump
recently signaled
he'd like the federal government to loosen that designation.
Even as many states moved to legalize medical and recreational marijuana, that didn't result in large investment in the kind of high-quality studies that medicine leans on when evaluating treatments.
Because the
Lancet Psychiatry
paper had strict criteria for which studies could be considered, the final analysis only included data from close to 2,500 patients. And for some conditions like depression, there was not a single trial available.
"It's embarrassing how little we have done in terms of data collection, given how widely this is available as a therapeutic," says
Ryan Vandrey,
a professor of psychiatry and behavioral sciences at Johns Hopkins University School of Medicine who studies cannabis.
Though done well, a review of this nature invariably comes with major limitations, he says. It collapses data from different products, doses, routes of administration, patient populations, and so on — and excludes the findings from long-term, observational studies and other sources of evidence.
"So it can be challenging to draw firm conclusions, especially when there's not that many actual studies or patients being evaluated," he says.
The Lancet Psychiatry
study comes on the heels of
another major review,
published earlier this month in
JAMA Internal Medicine
.
That took a broader view — considering other types of studies, not just controlled trials — but came to a similar conclusion on the lack of evidence for treating mental health conditions.
Children's Health
A huge study finds a link between cannabis use in teens and psychosis later
It also warns of "substantial risks" in vulnerable groups, including adolescents and young adults, those at risk of substance use disorders, as well as people with bipolar disorder or psychotic disorders. There is a
well-documented link
between cannabis use at a young age and an increased risk of psychosis
"What we wanted to do is convey that cannabis is not one thing because it's such a complex substance," says
Dr. Devan Kansagara
, a professor of medicine at Oregon Health and Science University and the Portland VA.
Kansagara, who runs a
project funded by the Department of Veterans Affairs
aimed at synthesizing the evidence on cannabis, says doctors need to speak with their patients who are using cannabis, whil

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## Expert Analysis

### Merits
- But a sweeping review of cannabis studies over the past 45 years concludes there is little to no high-quality evidence showing this is effective.
- Vandrey has been involved in several research studies that have shown "significant clinical benefit to patients with anxiety and depression," he says.
- Neither were included in the Lancet Psychiatry analysis because they didn't meet the criteria. "There's a subset of people with anxiety, depression, or PTSD that can realize tremendous benefit when they start using a cannabis product for that purpose," Vandrey says. "Now we also see that some patients try it and it really has no effect.

### Areas for Consideration
- Health Sparse evidence for cannabis to treat mental health conditions highlights research gap March 17, 2026 12:57 PM ET By Will Stone Many say they use cannabis for their mental health, but there's no evidence it helps Listen · 3:09 3:09 Transcript Toggle more options Download Embed Embed < iframe src="https://www.npr.org/player/embed/nx-s1-5750489/nx-s1-9690891" width="100%" height="290" frameborder="0" scrolling="no" title="NPR embedded audio player"> Transcript While many people turn to cannabis to help with mental health conditions, the scientific evidence is scant.
- Children's Health A huge study finds a link between cannabis use in teens and psychosis later It also warns of "substantial risks" in vulnerable groups, including adolescents and young adults, those at risk of substance use disorders, as well as people with bipolar disorder or psychotic disorders.
- There is a well-documented link between cannabis use at a young age and an increased risk of psychosis "What we wanted to do is convey that cannabis is not one thing because it's such a complex substance," says Dr.

### Implications
- Health Sparse evidence for cannabis to treat mental health conditions highlights research gap March 17, 2026 12:57 PM ET By Will Stone Many say they use cannabis for their mental health, but there's no evidence it helps Listen · 3:09 3:09 Transcript Toggle more options Download Embed Embed < iframe src="https://www.npr.org/player/embed/nx-s1-5750489/nx-s1-9690891" width="100%" height="290" frameborder="0" scrolling="no" title="NPR embedded audio player"> Transcript While many people turn to cannabis to help with mental health conditions, the scientific evidence is scant.
- Insomnia, autism and tic or Tourette's syndrome had more supporting data, though even that evidence was deemed "low quality" by the authors. "We clearly need to do more research on cannabis medicines," says Jack Wilson , a postdoctoral research fellow at the Matilda Centre for Research in Mental Health and Substance Use at the University of Sydney who led the review. "In the absence of evidence at this time, the routine use of medical cannabis products really should be rarely justified for the treatment of mental health disorders," he told NPR.
- National Marijuana rescheduling would bring some immediate changes, but others will take time The findings are not altogether surprising for cannabis researchers who know first-hand how challenging it is to conduct and fund well-controlled trials.
- Even as many states moved to legalize medical and recreational marijuana, that didn't result in large investment in the kind of high-quality studies that medicine leans on when evaluating treatments.

### Expert Commentary
This article covers cannabis, health, evidence topics. Notable strengths include discussion of cannabis. Areas of concern are also raised. Readability: Flesch-Kincaid grade 0.0. Word count: 1032.