NIH to Congress: Study link between increased cannabis use and psychosis, suicidal thoughts

A key National Institutes of Health official told Capitol Hill lawmakers they are right to be concerned about the potential link between increased use of recreational marijuana and psychosis.

Dr. Nora Volkow, director of the National Institute on Drug Abuse, said her office is trying to understand the link, given the rapid uptick in cannabis use, particularly products with higher concentrations of the active ingredient known as THC.

“It is the high doses that are associated with psychosis,” Dr. Volkow told the Senate Appropriations Committee. “So yes, we are prioritizing this scenario of research to try to unequivocally determine if there’s a causal link between the use of cannabis and psychosis.”

Psychosis is a mental illness that involves lost contact with reality.

Dr. Volkow was responding to Sen. Susan M. Collins, Maine Republican, who wanted to make sure NIH was on top of the issue, given trends in marijuana use among young people whose brains are still developing.

Many politicians and industry players are pushing lax pot policies, saying they advance social justice and equity without causing much societal harm.

Things have changed swiftly over the past decade. Colorado and Washington state became the states to legalize recreational marijuana in 2012. Since then, 19 states and the District of Columbia have joined them, though states have varying approaches to sales.

Smart Approaches to Marijuana, an organization that warns about the harm of marijuana use, issued a report last month that says 52.5 million Americans used marijuana in 2021 versus 17.5 million in 1992.

Marijuana flower is becoming more potent, the SAM report said, with the average concentration of THC increasing from 3.75% in 1995 to 15.8% in 2018.

Dr. Drew Pinsky, a physician known for his TV appearances and medical work on addiction, said he is witnessing the consequences at his practice.

“We are seeing psychotic episodes at an extraordinary rate,” Dr. Pinsky said at a D.C. summit hosted by SAM.

Dr. Volkow said it is a critical area of exploration.

“It’s a very important area of research to try and understand under what conditions the use of marijuana can result in psychosis and, importantly, chronic psychosis,” she said.

Some research in this area has been completed.

The NIH on Thursday said a major study by its scientists and Danish partners found young men who abuse marijuana have a higher risk of developing schizophrenia, a disorder in which people have difficulty participating in everyday activities.

The study examined health records data spanning five decades and representing more than 6 million people in Denmark to explore the link between cannabis use disorder and schizophrenia. Scientists determined 30% of cases of schizophrenia among men ages 21-30 might have been prevented by averting marijuana use.

The study team concluded young men are at particular risk. For instance, scientists said 15% of cases of schizophrenia among men ages 16-49 might have been avoided in 2021 by preventing cannabis addiction compared with 4% of women in the same age group.

Dr. Volkow on Thursday said researchers are also looking at the potential role of cannabis in suicidal behavior.

“From what we know,” she said, “we should be concerned and certainly be monitoring the trends.”

Keith Humphreys, a Stanford University professor who tracks addiction issues, said Dr. Volkow is correct to target the problem.

“For years, legalization activists trotted out, without evidence, the Iron law of Prohibition, which claimed that drugs got more potent only because they were illegal,” he said. “Cannabis legalization has shown this idea to be ridiculous: the legal industry is producing products of potency far higher than drug cartels ever did. And as Dr. Volkow says, this has significant potential to increase the damage that cannabis does to human health.”