Surprise! Cannabis use has been linked to schizophrenia, especially in young men. This news has been posted in several major news outlets, including The New York Post. The only thing newsworthy about this story is it qualifies as news.
As a physician, I have been aware of this connection since medical school, nearly fifty years ago! But politicians have been pressured to ignore this information since recreational marijuana use has been legalized now in 21 states and 18 more have legalized medical usage. With so many states making it possible to use marijuana, what could go wrong?
I went to college at The University of Colorado in the 1970s. The Boulder campus was filled with potheads and others in the hippie culture. Most of these people were not actually students, but their presence was ubiquitous and the pathology of their minds was undeniable; and that was before the much higher concentrated cannabis was available. Depression and schizophrenia were present then; it’s no surprise they’re even more common today.
The most recent research study was published May 4 in the journal Psychological Medicine. It found that a shocking 30% of schizophrenia cases among men aged 21 to 30 could have been thwarted if they had averted cannabis use disorder (CUD). Scientists examined recent cases of schizophrenia, an abnormal interpretation of reality resulting in hallucinations, delusions or disordered thinking. The study’s authors stated that in 2021, CUD played an integral role in 15% of cases occurring in men aged 16 to 49, and in 4% of cases affecting women in the same age range. This new study examined data concerning 6.9 million people ages 16 to 49 collected in Denmark from 1972 to 2021.
CUD is defined by the Centers for Disease Control and Prevention (CDC) as the inability to stop using marijuana despite negative impacts on one’s health and social life. (That’s a fancy way of saying marijuana is addictive.) According to the CDC, it affects 3 in 10 marijuana smokers. It is not surprising that men are at more risk for developing schizophrenia when smoking marijuana since the same male preponderance is found in non-smokers of marijuana as well.
Excessive use of marijuana in teens is especially dangerous since it can impact brain development and even cause some changes to its anatomy. “The brain is at its peak developmental years from 12 to 20,” said Dr. Scott Krakower, a psychiatrist at Northwell Health’s Zucker Hillside Hospital in an interview with The New York Post. “When marijuana comes into the picture, the normal brain development is impaired.”
“There could be changes to the overall neuroplasticity and neurocircuitry. . . changes to serotonin, changes to dopamine, histamine, all these things are responsible for executive functioning and for how we perceive the world,” he continued. “When cannabis oversaturates the system it can trigger higher levels of anxiety, cognitive delays, and memory loss.”
Teens are also more likely to develop a problem with the drug. According to a report by the National Institute on Drug Abuse published in March, 2021, those aged 12 to 17 are more apt than those aged 18 to 25 to become addicted to marijuana within a year after using it for the first time.
The Danish study determined that while cannabis use disorder is not responsible for most schizophrenia cases in Denmark specifically, marijuana consumption has contributed to a rise in schizophrenia in the last 50 years. Researchers say one possible reason is that cannabis is both more accessible and more powerful than ever. They found that the amount of THC – the major psychoactive component – in weed in the U.S. rose from 10% in 2009 to 14% in 2019. In Denmark it was 13% in 2006 and 30% in 2016.
For comparison, the THC in weed when I was in college was typically less than 1.5% in the 1970s and 1980s, according to previous research published int the Journal of Forensic Sciences. Today, some cannabis products contain THC concentrations upward of 30%. Some concentrated products such as oils and edibles can have above 95%.
Dr. Krakower says, “A lot of these products are mislabeled. When you’re looking at the weed market, nothing is regulated – you always have to know in the back of your head if you’re having 5mg you might be having 10 or 15 mg- there’s just no way of knowing. The problem is, people forget that marijuana is still a substance no matter how we look at it. Parents need to understand that it’s not healthy.”
That’s not news. I could have told you that 50 years ago!
