Editor’s note: David L. Nathan, MD, is a psychiatrist, educator, and founder and president of Physicians for Drug Policy Reform (d4dpr.org). Dr. Peter Grinspoon is a primary care physician and cannabis expert at Harvard Medical School. He is the author of the recent book, “Seeing Through the Smoke: Cannabis Experts Reveal the Truth About Marijuana,” and is a board member of the Physicians for Drug Policy Reform. The views expressed in this commentary are their own.view more opinions On CNN.
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Among the many harms of cannabis use, few have received as much attention as the frightening link between cannabis and mental illness. From the 1936 exploitation film “Reefer Madness” to a recent article in the Wall Street Journal, the media has covered this topic extensively, and sometimes exaggeratedly. Still, the question remains: Does cannabis really cause psychosis and related illnesses such as schizophrenia, or is this also an exaggerated claim?
The link between cannabis use and psychosis is well established by research. There is no doubt about this association. However, as we all learn in high school science, correlation does not imply causation. Let’s consider a common example. Ice cream consumption and drowning both increase in summer. They are definitely related. But no one believes that one of these causes the other. It is especially important for us doctors to figure out whether cannabis actually exists. cause Mental illness.
Let’s start by defining “mental illness”. This is a disconnection from reality and includes delusions, hallucinations, and/or confusion of thought. Delusions may be paranoid or frightening in nature. Psychotic episodes can last from days to months or even years. Even a brief psychotic episode can mark the beginning of a lifelong mental illness, such as bipolar disorder or schizophrenia.
Through decades of clinical research, we have seen many cases of psychosis that first emerged in connection with cannabis use. On the one hand, this is not surprising since people are likely to start using cannabis at the same ages when they are most at risk for a first episode of psychosis, i.e. in their teens or 20s. However, we have seen many cases where the timing was too close to dismiss as mere coincidence.
It may be easy, especially for those who want to condemn cannabis use, to claim that cannabis use causes psychosis or schizophrenia without looking closely at the correlation between the two. However, the available evidence does not support such a simple view, as there are several other possible associations.
For example, people at risk for psychosis may self-medicate with cannabis before developing a psychotic disorder. In this scenario, before psychosis develops, the patient may experience anxiety and use cannabis in an attempt to feel better. Cannabis may not help, but it often doesn’t actually cause psychosis. Paradoxically, acute psychotic symptoms can lead people to self-medicate with cannabis. This means that in some cases, mental illness is the cause of cannabis use and not the other way around.
Second, cannabis can cause or worsen psychosis, even if it is not the primary cause. We know that other drugs, such as psychostimulants, steroids, hallucinogens, and alcohol, can also cause short-term substance-induced psychosis, which can last from days to months. Still, of all the drugs associated with this rare type of psychosis, cannabis is the most common culprit.
Among people with substance-induced psychosis, those who use cannabis are most likely to eventually progress to schizophrenia.That’s right It shows As if cannabis causes not only temporary psychosis but also schizophrenia. At the same time, studies have shown that these patients have a higher genetic risk for schizophrenia, meaning that cannabis may simply predispose patients to ultimately suffering.
To further complicate matters, there is a third explanation for the relationship between cannabis and mental illness.There is some evidence that certain genes may predispose people to both types of cannabis use. and Psychosis, a common genetic basis.
Well, where does all this leave us?
Cannabis is unlikely to be used alone cause schizophrenia. Although the prevalence of schizophrenia has remained stable for the past 70 years, the rate of global cannabis use has increased from a few hundred thousand people in the 1950s to hundreds of millions today.If it’s cannabis caused In the case of schizophrenia, if cannabis use increased a thousand times, the incidence of schizophrenia would also rise, but it hasn’t.
Still, if cannabis can accelerate the onset of schizophrenia in vulnerable populations, that in itself is a public health problem. The early onset of schizophrenia means that patients have a short period of biological and psychological development before the mental illness negatively impacts brain development and adult coping abilities. It can lead to worse outcomes, including positive symptoms of schizophrenia such as paranoia and delusions.
Given the continuing uncertainty surrounding this issue, people with a history of schizophrenia or other psychotic disorders may have compelling medical reasons to use cannabis under close clinical supervision. Unless you have it, it would be wise to avoid cannabis completely. Even if you have a relative with a psychotic disorder or other serious mental illness, you should think carefully and use caution before using cannabis. We also don’t know if strong cannabis, with very high THC (tetrahydrocannabinol) concentrations, is more likely to cause or worsen psychosis, but it may be the case.
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Interestingly, there is some evidence that the second most common cannabinoid molecule, CBD, has mild antipsychotic activity. Therefore, cannabis with high levels of CBD may have a lower risk of causing psychosis, and cannabis with CBD without THC may actually benefit people with schizophrenia in combination with other antipsychotics. may bring. Consumers need to be careful here too. The U.S. Food and Drug Administration does not yet regulate CBD products, so untested products may contain more THC than the 0.3% limit allowed by law. CBD products should only be purchased from reputable companies that test their products through independent laboratories and share their results.
Given the increasing normalization and acceptance of cannabis in society, it is as important as ever to understand the real benefits and risks associated with its use. People use cannabis to relieve chronic pain, nausea, insomnia, and many other symptoms.
Of course, no drug is completely safe for everyone, and all have potential side effects. Cannabis use can be made safer by encouraging people to consume products with lower THC levels and higher CBD levels. Perhaps most importantly, for teens and young adults with risk factors for psychosis, delay cannabis use until after the age when psychotic disorders such as schizophrenia are most likely to first develop. This means that we need to encourage Although we should not jump to the conclusion that cannabis causes psychosis, people planning to use cannabis should understand their own risk factors and take precautions accordingly.