Liz Kirkaldie’s grandson was near the top of his class in high school and a talented jazz bassist when he started smoking pot. The more serious he got about music, the more serious he got about pot.
And the more serious he got about pot, the more paranoid, even psychotic, he became. He started hearing voices.
"They were going to kill him and there were people coming to eat his brain. Weird, weird stuff," Kirkaldie said. "I woke up one morning, and no Kory anywhere. Well, it turns out, he’d been running down Villa Lane here totally naked."
Kory went to live with his grandmother for a couple of years in Napa, California. She thought maybe she could help. Now, she says that was naive.
Kory was diagnosed with schizophrenia. Kirkaldie blames the pot.
"The drug use activated the psychosis, is what I really think," she said.
Indeed, many scientific studies have linked marijuana use to an increased risk of developing psychiatric disorders, including schizophrenia. The risk is more than four times as great for people who use high-potency marijuana daily than for those who have never used, according to a study published in The Lancet Psychiatry in 2019. One study found eliminating marijuana use in adolescents could reduce global rates of schizophrenia by 10%.
Doctors and lawmakers in California want cannabis producers to warn consumers of this and other health risks on their packaging labels and in advertising, similar to requirements for cigarettes. They also want sellers to distribute health brochures to first-time customers outlining the risks cannabis poses to youths, drivers, and those who are pregnant, especially for pot that has high concentrations of THC, the chemical primarily responsible for marijuana’s mental effects.
"Today’s turbocharged products are turbocharging the harms associated with cannabis," said Dr. Lynn Silver with the Public Health Institute, a nonprofit sponsoring the proposed labeling legislation, SB 1097, the Cannabis Right to Know Act.
Californians voted to legalize recreational pot in 2016. Three years later, emergency room visits for cannabis-induced psychosis went up 54% across the state, from 682 to 1,053, according to state hospital data. For people who already have a psychotic disorder, cannabis makes things worse — leading to more ER visits, more hospitalizations, and more legal troubles, said Dr. Deepak Cyril D’Souza, a psychiatry professor at Yale University School of Medicine who also serves on the physicians’ advisory board for Connecticut’s medical marijuana program.
But D’Souza faces great difficulty convincing his patients of the dangers, especially as 19 states and the District of Columbia have legalized recreational marijuana.
"My patients with schizophrenia and also adolescents hear very conflicting messages that it’s legal; in fact, there may be medical uses for it," he said. "If there are medical uses, how can we say there’s anything wrong with it?"
Legalization is not the problem, he said; rather, it’s the commercialization of cannabis — the heavy marketing, which can be geared toward attracting young people to become customers for life, and the increase in THC from 4% on average up to between 20% and 35% in today’s varieties.
Limiting the amount of THC in pot products and putting health warnings on labels could help reduce the health harms associated with cannabis use, D’Souza said, the same way those methods worked for cigarettes.
He credits warning labels, education campaigns, and marketing restrictions for the sharp drop in smoking rates among kids and teens in the past decade.
"We know how to message them," D’Souza said. "But I don’t think we have the will or the resources, as yet."
Some states, including Colorado, Oregon, and New York, have dabbled with cannabis warning-label requirements. California’s proposed rules are modeled after comprehensive protocols established in Canada: Rotating health warnings would be set against a bright-yellow background, use black 12-point type, and take up a third of the package front. The bill suggests language for 10 distinct warnings.
Opponents of the proposed labels say the requirements are excessive and expensive, especially since marketing to children is already prohibited in California and people must be 21 to buy.
"This bill is really duplicative and puts unnecessary burdens on the legal cannabis industry, as we already have incredibly restrictive packaging and advertising requirements," said Lindsay Robinson, executive director of the California Cannabis Industry Association.
The state should focus more on combating the illicit pot market rather than further regulating the legal one, she said. Legal dispensaries are already struggling to keep up with existing rules and taxes — the state’s 1,500 licensed pot retailers generated $1.3 billion in state tax revenue last year. Adding more requirements makes it harder for them to compete with the illicit market, she said, and more likely to go out of business.
"The only real option if they fail out of the legal system is to shutter their businesses altogether or to operate underground. And I don’t think the state of California, with the tax revenue, wants either of those to happen," Robinson said. "The heart of the issue is that there’s a massive, unregulated market in the state."
Some people are skeptical that the labels will work. Liz Kirkaldie’s grandson, Kory, is stable now, living with his dad. But she’s not sure a yellow warning would’ve stopped him when he was a teen.
"They’re just not going to pay attention," she said. "But if it helps even one person? Great."
Scientists still do not know what causes schizophrenia, but they believe multiple factors are at play, including genetics, family history, trauma, and other influences in a person’s environment, like smoking pot. Some scientists believe having schizophrenia in the first place predisposes people to smoking pot. While it’s difficult to prove a direct causal link between cannabis use and schizophrenia, the associations are strong enough to warrant action, said D’Souza, and, importantly, pot use is one of the few risk factors people can control.
"Not everyone who smoked cigarettes developed lung cancer, and not everyone who has lung cancer smoked cigarettes," he said. "But I think we would all agree that one of the most preventable causes of lung cancer is cigarette smoking."
Applying the same health education strategies to cannabis that were used for tobacco, he said, is long overdue.
KHN (Kaiser Health News) is a national newsroom that produces in-depth journalism about health issues. Together with Policy Analysis and Polling, KHN is one of the three major operating programs at KFF (Kaiser Family Foundation). KFF is an endowed nonprofit organization providing information on health issues to the nation.