'Cannabis Use Increasing in People With Psychosis'

 

• After states passed laws legalizing recreational cannabis, past-month use among people with psychosis increased by nearly 10 percentage points.
• People with psychotic disorders who use cannabis experience a greater symptom burden, worse functioning, and more and longer hospitalizations.
• Regulatory changes such as potency caps, changes in taxation, and warning labels could help address some of these preventable harms for people with psychosis.

Cannabis use increased among people with psychosis after states legalized the substance for recreational use, according to a longitudinal cohort study.

In states where recreational cannabis was legalized, 30-day cannabis use increased by 9.53 percentage points (95% CI 3.05-16.00, P=0.004) among people with psychosis, reported Andrew S. Hyatt, MD, of Harvard Medical School in Boston, and co-authors in JAMA Psychiatry.

That increase was well above the 3.3-percentage point increase in past-month cannabis use among the general population observed in a recent study.

Sensitivity analyses in the current study showed no significant increase in cannabis use before cannabis retail outlets opened. Weekly use did not significantly change, Hyatt and team said.

As of 2024, 24 states and the District of Columbia have legalized cannabis for adult recreational use.

This study is the first to quantify trends in cannabis use in people with psychotic disorders following state-level legalization and commercialization, the authors noted.

The roughly 10% increase is "fairly large," Hyatt told MedPage Today. It "means that an additional one in 10 people with a history of psychosis who were not previously using cannabis are [now] using cannabis, at least in part due to the effects of legalization."

Hyatt and his team pointed out that "while many individuals use cannabis without significant harm, individuals with psychotic disorders who use cannabis have a higher symptom burden, worse functioning, more and longer hospitalizations, and higher relapse rates compared with non-users."

Brendan Saloner, PhD, of the Brown University School of Public Health in Providence, Rhode Island, told MedPage Today that legalization has always focused on striking the right balance between risks and benefits.

"As a parent, I think a lot about what kind of environment I want my kids to grow up in, and I think that there's a need for us to think about how to, in some ways, rein in a social experiment that went a little too far in the wrong direction," he said.

Hyatt noted that there are many ways to reduce the harms from cannabis. For people with psychosis, products with high tetrahydrocannabinol (THC) content, which contributes to mental health effects and increases the risk for addiction, are a big concern.

In the late 1960s, the average THC concentration was 5%. Today, it's about 20%. Newer products like "waxes," "dabs," and "shatters" have concentrations as high as 90%, Hyatt explained.

"If there was only one thing that we could do, I think it would be regulating those products a lot more closely," he said, pointing out that Uruguay, for example, capped potency at 9% and Canada proposed taxing cannabis by potency rather than weight.

Saloner noted that taxation is an important strategy because the cheaper cannabis is, the more frequently people will use it. But just passing caps isn't enough; in the face of an "aggressive black market," there needs to be enforcement, he said.

Warning labels can also be very helpful, but need to have simple, clear messages for people of all literacy levels, he added.

For this study, Hyatt and team used data from 2014 to 2022 on state-level recreational cannabis legalization with 5 years of follow-up from the Population Assessment of Tobacco and Health, a national survey that collects individual-level data on substance use and health conditions. They compared cannabis use among people with a history of psychosis in states that legalized cannabis to the same subpopulation in states that never legalized cannabis. Past-month use of cannabis was based on an affirmative response to the question: "In the past 30 days, have you used marijuana, hash, THC, grass, pot, or weed?"

The study sample included 1,856 individuals with a history of psychosis, who shared 7,465 responses. Mean age was 36.6, 50.2% were white, 58.2% were women, and the 30-day cannabis-use rate was 31.8%.

To improve model precision, the authors adjusted for self-reported race and ethnicity, receipt of antipoverty assistance, sex, and age.

Hyatt noted that people with serious mental illnesses are under-represented in research, and while this study includes a "decent" sampling of this subgroup, a larger sample would give the team even more confidence in their findings.

Disclosures

The study was supported by grants from the National Institute on Drug Abuse and the National Institute on Mental Health.

The authors disclosed no conflicts of interest.

Primary Source

JAMA Psychiatry

Source Reference: Hyatt AS, et al "Cannabis use among individuals with psychosis after state-level commercial cannabis legalization" JAMA Psychiatry 2025; DOI: 10.1001/jamapsychiatry.2025.2539.

https://www.medpagetoday.com/psychiatry/generalpsychiatry/117848