In the past decade of diagnosing countless young patients with new psychotic disorders, one striking result has emerged for New York psychiatrist Dr. Ryan Sultan.
“Of all the people I’ve diagnosed with a psychotic disorder,” he said, “I can’t think of one who wasn’t so positive for cannabis.”
Sultan, an assistant professor of clinical psychiatry at Columbia Irving Medical Center, is one of many experts who are seriously concerned about the increase in marijuana use by teens and young adults.
And the evidence for the association of marijuana with psychiatric disorders such as depression, bipolar disorder and schizophrenia, particularly in young men, is mounting.
New research published this month, involving millions of people around the world for decades, adds to concerns that the extensive use of high-potency cannabis and the legalization of recreational weed in many US states could exacerbate the the country’s mental health crisis among young adults.
“There’s a great sense of urgency not only because more people are smoking marijuana, but because more people are using it in harmful ways, with higher and higher THC concentration,” said the Dr. Nora Volkow, director of the National Institute on Drug Abuse (NIDA), said in an interview.
One of the studies, conducted by researchers in Denmark in conjunction with the US National Institutes of Health, found evidence of an association between cannabis use disorders and schizophrenia. The finding was most striking in young men between the ages of 21 and 30, but was also seen in women of the same age.
The article, published in the journal Psychological Medicine, looked at data from nearly 7 million men and women in Denmark over a few decades to look for a link between schizophrenia and cannabis use disorders.
The magnitude of the link between cannabis and schizophrenia in young men surprised study author Volkow, who expected the number to be closer to 10%.
“It’s worrying,” she said.
There are now 22 states that allow the recreational use of marijuana, with Minnesota likely to become the next state to legalize it.
It’s unclear whether recreational cannabis laws are contributing to underage use, but Volkow has made tackling teenage cannabis use one of NIDA’s top priorities. Daily marijuana use among young adults has reached record highs, with more than one in 10 young adults aged 19 to 30 reporting daily use and nearly half reporting use in the past year, according to the agency’s most recent data.
Another study, led by researchers at Sultan and Columbia and published earlier this month, found that teens who use cannabis only for recreational purposes are two to four times more likely to develop psychiatric disorders, including depression and suicide than adolescents who do not use cannabis at all.
Because research to date has been observational and does not directly prove cause and effect, the link between marijuana and psychiatric disorders is controversial. It is unclear whether people who already have or develop psychiatric disorders are more likely to turn to cannabis as a means of self-medication or whether cannabis use triggers mental problems.
Volkow is optimistic that a large, ongoing study of adolescent brain development at the National Institutes of Health can help answer that question.
Sultan acknowledged the limitations of the evidence. “It’s kind of a circular feedback where they kind of feed off of each other,” he said.
Dr Deepak D’Souza, a Yale University psychiatrist who has studied cannabis for 20 years, insists there is too much evidence to ignore.
“We may be grossly underestimating the potential risks associated with cannabis,” he said.
Given the increasing legalization and growing potency of cannabis products, D’Souza has never been more concerned about the mental health effects of cannabis use among young people.
“It’s a major concern,” he said. “We have been woefully unable to educate the public and influence policy.”
Does Legalization Affect Marijuana Use Rates?
Early data suggests that among young adults ages 18 to 25, legalization leads to higher rates of cannabis use, particularly in Oregon and Washington, according to analysis published earlier this month in the Substance Abuse magazine.
The research, led by researchers at McMaster University in Canada, found the evidence in other age groups to be somewhat less clear, and further research is needed to understand how legalization affects rates of cannabis use. .
In areas where marijuana is becoming legal and easier to access, Volkow’s concern is how easily the products can be mixed, leading to a high total dose of marijuana consumed.
One of the biggest problems, she says, is the lack of regulation on the concentration of THC in products.
Marijuana consumed decades ago had concentrations of THC, the main psychoactive ingredient, of 2-3%, but today’s cannabis products can have THC levels as high as 90%.
“That’s not even the case with alcohol because you can’t put more than a certain percentage of alcohol in alcohol,” she said. “The same with tobacco cigarettes, you regulate how much nicotine they contain. Here we have no regulations.
The potency of THC matters, Volkow said, because cannabis is more likely to be linked to psychosis with higher doses consumed.
What age is the most vulnerable?
Research has shown that the human brain is the last organ to fully develop and doesn’t finish until your mid-twenties. This makes teenagers and young adults particularly vulnerable to the effects of cannabis as their brains continue to mature.
“Really, the ideal time to consider using weed — if you’re going to use it — is 26 or older,” Sultan said.
People who wait until they are 26 are much less likely to become addicted or develop mental disorders, said Dr. Sharon Levy, a pediatrician and addiction specialist at Boston Children’s Hospital.
“The greatest risks are clearly in the adolescent and young adult age group,” she said.
However, people with a family history of psychotic disorder should not use cannabis at all, warned Sultan.
What does cannabis do to the brain?
Although scientists are still learning about the effects of marijuana on brain development, studies so far suggest that marijuana use in adolescents may affect functions such as attention, memory and learning. , according to several studies.
“It kind of interferes with the connections we use in our brain to distinguish between what’s going on inside our head and what’s going on outside our head,” Levy said in reference to the psychotic symptoms that can occur.
D’Souza added that cannabis use can have serious repercussions on the developing brain due to its effects on the endocannabinoid system, a complex signaling system in the brain targeted by marijuana.
“Endocannabinoid systems play an important role in brain sculpting during adolescence, which is when schizophrenia typically manifests,” he said.
Disrupting this system with cannabis use could have “complex, far-reaching implications for brain development.”