Alibi V.28 No.16 • April 18-24, 2019 

Cannabis Manual

Cannabis and Psychosis

A puzzling relationship

headbrain

“Is Marijuana as Safe as We Think?”

That was the title of a New Yorker article published earlier this year that threw many of us cannabis advocates into a monumental tizzy.

The piece, written by Malcolm Gladwell, starts off reasonably enough, citing a 2017 report released by the National Academy of Medicine—which found few conclusive answers to health questions surrounding marijuana—and bemoaning the lack of research available on the effects of cannabis, but quickly turns barbed when it begins to reference Alex Berenson’s forthcoming book Tell Your Children: The Truth About Marijuana, Mental Illness, and Violence.

Berenson correlates marijuana use with a supposed rise in what he says is a new kind of mental illness that seems similar to schizophrenia. He also connects a rise in cannabis use with a rise in violent crimes, presumably due to psychotic episodes that could allegedly be caused by the drug.

In a subsequent Seattle Times article, a number of cannabis scientists criticized Gladwell's research. Beatriz Carlini, senior research scientist at the University of Washington’s Alcohol & Drug Abuse Institute, said the violent crime statistics reported by Gladwell are misleading. He cites a 17 percent increase in violent crime in Washington between 2013 and 2017. Carlini pointed out that there was a large dip in the number of violent crimes committed in 2012, meaning that the statistic wasn't rising—it was just returning to where it was before 2013. The Seattle Times article also points to FBI statistics that show that between 2007 and 2017, Washington's violent crime rates were still below the national average.

A New York Times piece by Benedict Carey compares Berenson's book to Reefer Madness, taking aim at its claims that marijuana use can lead to psychosis and schizophrenia. As it points out, while there is evidence that biological mechanisms might lie behind psychotic disorders, determining whether one caused the other is hard to do. Carey also mentions a 2015 study conducted by researchers at Virginia Commonwealth University that found smoking nicotine cigarettes was a predictor for later development of schizophrenia. The number of marijuana users who developed schizophrenia later in life who were also cigarette smokers remains unclear and unaddressed. However, most experts seem to agree that marijuana, like any psychoactive substance (including nicotine and caffeine), can trigger a psychotic episode in someone who is already prone to one.

That's because cannabis—and all psychoactive compounds—can be a source of stress, and stressors are the number one cause of psychotic episodes, according to the National Alliance on Mental Illness. Bouts of schizophrenia are generally marked by these episodes, but it isn’t believed that they’re caused by them. While the jury's still out, it's commonly accepted that schizophrenia is caused by genetic abnormalities combined with environmental factors. If this is the case, then someone who suffers a psychotic break brought on by cannabis use and leading to a diagnosis of schizophrenia almost certainly would have had said break regardless of the stressor.

So what does this all mean? Well it seems marijuana probably won't cause you to develop psychosis … unless you were already prone to develop psychosis. This is good news for most of us, but it also means that the general consensus of cannabis being “completely safe” isn't exactly accurate. This is why bringing the subject up with your healthcare provider is a good idea before experimenting on your own. It's also a good reason to keep this drug out of the hands of teenagers, since symptoms of psychosis and schizophrenia generally show up between the ages of 18 and 24, according to Early Psychosis Intervention Advanced Practice Project.

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