Most recently, a new study published by The Lancet Psychiatry Journal further fuels the hesitancy found in the conversation surrounding the legalization of cannabis. The 2019 study joins the ranks of research exploring the possible correlation between frequent use of THC-dominant cannabis products and the risk of having a psychotic episode.
Psychosis, which is characterized as disruptions in a person's thoughts and perceptions that make it difficult to decipher the difference between what is and isn't reality, is something that 3 in 100 people are said to have experienced at some point in their lives. Additionally, approximately 100,000 young people will experience a psychotic episode each year in the United States. That being said, warning signs for early psychosis or FEP can be hard to recognize and rarely happen suddenly. Because psychosis often begins when a person is in their late teens to mid-twenties—which is also part of the age bracket representing the highest support for cannabis legalization—both subject areas are of interest to study and examine more closely. As first published by The Lancet Psychiatry Journal earlier this year, there is evidence showcasing that daily cannabis use, especially that of high potency cannabis, is "strongly linked" to the risk the user has of possibly developing psychosis.
The case-control study, which took place across 11 sites throughout Europe, included more than 900 participants who had been diagnosed with at least one episode of psychosis and a control group of 1,100 "healthy" people who had not experienced psychosis. The study found that those who did smoke marijuana daily were three times more likely to experience a psychotic episode than those who had never tried consuming the substance. The study also noted that the risk increased among those who began smoking as teenagers. Additionally, the risk of having a psychotic episode increased for those who consumed high-potency cannabis products containing more than 10% of THC (the psychoactive compound derived from the plant).
While the study is not necessarily the first of its kind, it is the first noting how cities with more easily available high-THC cannabis products do have a higher rate when it comes to new psychosis diagnoses. However, additional research is needed for the possible link and risk factors of frequent cannabis usage to psychosis. In European cities like London and Paris, higher potency marijuana is available, but due to its status as an illegal drug, it is purchased through the black market. This poses a problem with the study, as there is no way to determine if the cannabis that was consumed also contained pesticides, mold or other contaminants. This also makes it difficult to measure the exact potency of the THC content, which is another criticism of the study.
As NORML Deputy Director Paul Armentano pointed out to Rolling Stone, the study in question is limited due to the inability to know if the subjects who consume marijuana are already more predisposed to symptoms of psychosis in the first place.
"At the end of the day we know that people suffering from psychosis generally use all intoxicants, including cigarettes, at greater levels than the general population — so it is hardly surprising that these folks also tend to use cannabis in greater percentages," Armentano explains. "But it is a leap and remains unsubstantiated to allege that cannabis exposure triggers a psychotic break in those non-predisposed."
While the study's findings raise an alarming point, the biggest takeaway once again signals the need for more research on cannabis, especially in relation to how it can possibly impact physical and mental health in the long-term.