Using medical or recreational marijuana doesn’t work to reduce the symptoms of many mental health conditions, according to two new analyzes of current gold-standard research.
Medical marijuana includes products with cannabidiol, or CBD, and delta-9-tetrahydrocannabinol, or THC, the part of the plant that produces euphoria.
“We haven’t found evidence that any form of cannabis is effective in treating anxiety, depression or post-traumatic stress disorder, the three leading reasons why cannabis is prescribed,” said Jack Wilson, a postdoctoral research fellow for research in mental health and substance use at the University of Sydney’s Matilda Centre.
Wilson is the lead author of a study published Monday in the Lancet Psychiatry journal, which analyzed the results of 54 randomized controlled trials between 1980 and 2025.
“The cannabis drugs administered in these studies were largely oral formulations, such as capsules, sprays or ointments,” he said. “In real life, people commonly use smoking, and there is even less evidence of its effectiveness for mental health.”
Marijuana use also did not improve other mental health conditions such as anorexia nervosa; bipolar disorder; obsessive-compulsive disorder, or OCD; or mental disorders such as schizophrenia, Wilson said.
Studies on marijuana are often small and difficult to conduct, experts say. Still, the randomized controlled trials that make up the Lancet review are the gold standard of research, said Dr. Deepak Cyril D’Souza, the Vikram Sodhi Professor of Psychiatry ’92 and director of the Yale Center for the Science of Cannabis and Cannabinoids in New Haven, Connecticut.
D’Souza, who was not involved in the Lancet study, is the senior author of a recent JAMA article that also explored the effects of natural and synthetic forms of CBD and THC on mental health conditions.
“These two documents clearly show that there is no evidence to recommend the use of hemp or cannabis derivatives for mental health treatment,” D’Souza said. “Nearly every state in the United States legalizes medical marijuana for mental health conditions.”
While there is little evidence of benefit, medical and recreational marijuana use for mental health is on the rise, experts say. About 27% of people between the ages of 16 and 65 in the United States and Canada use marijuana for medical purposes, “about half of them use it to manage their mental health,” Wilson said.
“Despite the lack of evidence of effectiveness, doctors continue to prescribe medical marijuana to treat mental health conditions,” he added. “Furthermore, the cannabis industry has ties to some of these studies, which is a conflict of interest that may affect the findings.”
Regular use of strong marijuana can be dangerous, experts say, especially to the most vulnerable. Marijuana use during pregnancy, adolescence and young adulthood can interfere with brain development. Heavy marijuana use by teens and young adults with mood disorders — such as depression and bipolar disorder — is associated with an increased risk of self-harm, suicide attempts, and death.
In people at high risk of bipolar or psychotic disorders, such as people with a family history, studies show that marijuana use increases the risk of developing a psychotic or mental health disorder. Its use after the onset of a psychotic state can impair cognition and increase the chance of relapse.
“While there may be thousands, perhaps millions, of people who use marijuana briefly, in very small amounts and experience no adverse events, we also know of people who have used marijuana many times and have experienced catastrophic adverse events that have changed the course of their lives forever,” D’Souza said.
“If you’re a daily user of high-strength marijuana, for example, you may be six times more likely to develop a mental illness like schizophrenia or bipolar disorder than someone who has never used marijuana,” he said.
Today’s weed is very powerful and addictive
Contributing to the problem: The amount of THC in today’s marijuana has risen from about 4% in the 1970s to an average of 18% to 20% today, D’Souza said.
“You can now buy marijuana in dispensaries that has a THC content of 35%,” he said. “The concentration of marijuana, which is similar to the concentration of nicotine, has a THC content of 80%. This is about 20 times greater than the THC content of marijuana from the 1960s and 70s.”
The high potency of weed also contributes to increased addiction. In the United States, about 3 in 10 people who use marijuana have marijuana use disorder, the medical term for marijuana addiction, according to the US Centers for Disease Control and Prevention.
Cannabis use disorder, also known as marijuana use disorder, is related to the use of weed. According to the National Institute on Drug Abuse, people are considered addicted to weed when they experience cravings or lack of appetite, irritability, insomnia, and mood and sleep problems after quitting.
Experts say there are proven methods for treating mental health concerns. Selective serotonin reuptake inhibitors, known as SSRIs, are a common medication for depression and anxiety.
The leading psychological treatment for these conditions is cognitive behavioral therapy, or CBT, which is often combined with SSRIs. Cognitive behavioral therapy is goal-oriented and focuses on changing negative thoughts and behaviors to improve emotional regulation and mood.
The Association for Behavioral and Cognitive Therapy has a list of therapists trained in CBT that is searchable by zip code. The American Psychological Association also lists CBT-trained therapists under “Therapy Methods” in its “Find a Psychologist” tool.
Get weekly inspiration on living well, made simple. Sign up for CNN Live, the best newsletter for information and tools designed to improve your well-being.
#marijuana #relieve #anxiety #depression #Science #shows #evidence #CNN