Science Shows Cannabis Does More Harm than Good

We have reached a crossroads in our society. A substantial portion of Americans embrace the message that cannabis is benign, even beneficial. In fact, it’s the most commonly used federally illegal drug in the United States; 49.6 million people, or nearly 18% of Americans, used it at least once in 2020, according to the Substance Abuse and Mental Health Services Administration (SAMHSA). Cannabis is commonly touted as a safe alternative to alcohol by those who sell it and consume it. Yet, we in the behavioral health sector observe a sharp rise in teens and young adults coming into residential treatment with significant mental health and cognitive disorders, largely driven by cannabis use.

Most Americans have easier access to cannabis now that 38 states and Washington D.C. have legalized it for medical use and 18 states and Washington D.C. have legalized it for recreational use – both for adults over the age of 21. But what’s perhaps most concerning is that current legislative policy is reinforcing wellness messaging around cannabis, without the science to back it up.

Pennsylvania is a prime example. The list of conditions for which people are certified to use cannabis medicinally is far too broad. Medicinal cannabis is even indicated as a treatment for opioid use disorder. This is a huge mistake because it ignores the evidence-based and peer-reviewed science behind proven medication-assisted treatments.

The Philadelphia Inquirer recently reported that the Pennsylvania Department of Health recalled marijuana vapes, which speaks to the larger issue of an unregulated marketplace posing as a health product with little to no research to back it up. This is yet another example of rushing into making cannabis products available. We need to slow down and let medical policy be driven be by research.

Caron does not support the legalization of cannabis products, especially in this unregulated environment that increases pressure on an already underfunded and under-resourced education, prevention and treatment system. And while it's true that, unlike opioids, people generally don’t die of a cannabis overdose, more must be done to help those being deceived by aggressive marketing tactics into thinking cannabis products are safe.

In fact, the 2020 SAMHSA data paint a much darker picture. Among people aged 12 or older, 5.1% (14.2 million people) had a marijuana use disorder in the past year. It is even worse among young adults aged 18 to 25, where 13.5% (4.5 million people) had a marijuana use disorder, compared to the percentages of adolescents aged 12 to 17 (4.1% or 1.0 million people) or adults aged 26 or older (4.0% or 8.7 million people).

The data also clearly suggest that repeated exposure to cannabis – prolonged and greater frequency of use – puts people at much greater risk of other substance use disorders and mental health disorders, such as psychosis and cognitive impairment, and it’s happening more frequently.

Likewise, researchers at Massachusetts General Hospital, whose findings were reported in the JAMA Network Open, found that individuals using cannabis to seek relief from anxiety and depression were at greatest risk of developing the addictive symptoms of cannabis use disorder (CUD), suggesting the need for stronger safeguards over the dispensing, use and professional follow-up of people who legally obtain cannabis through medical marijuana cards (MMC).

Adults are also at increased risk for the adverse consequences of cannabis use, including impaired driving, personal injury, and poorer outcomes in treatment for trauma and depression.

Simply put – there’s not enough science to back all the claims. So, let’s take a closer look at the risks.

The association between cannabis use and schizophrenia is well established. Smoking cannabis daily doubles the likelihood of developing psychotic symptoms. What is less clear is whether cannabis triggers the development of these symptoms or if people developing psychotic symptoms are self-medicating with cannabis. Increasingly, it is looking like cannabis is the driver.

This is particularly true in people with a genetic predisposition to schizophrenia. Studies have shown that people with siblings who have been diagnosed with schizophrenia are up to 15 times more likely to exhibit psychotic symptoms after recent cannabis use. This is borne out in our own experiences at Caron, where we have seen siblings come into treatment with similar responses to first or second cannabis exposures, with significant psychotic symptoms and manic symptoms.

One potential genetic risk factor is a variant of the AKT1 gene, which was found in a 2016 study to be a significant predictor of acute psychotomimetic symptoms associated with cannabis. Interestingly, the AKT1 variant was not associated in the study with cannabis dependence. There are many other factors at work here that we do not yet understand, and much more research is needed before we can say with any confidence that a particular person is definitively at lower risk in using cannabis.

One bright spot is that anonymous genetic data on many of the participants in the NESARC-III survey is now available for researchers. More than 36,000 people aged 18 and older were interviewed in 2012-2013 on their drug and alcohol use and general mental health, and roughly 23,000 of these participants also provided samples of their DNA. This represents a tremendous opportunity for researchers to identify a potential link between genetics and how people react to substances like alcohol and cannabis.

So, what should be our takeaways? We need to take these 5 steps immediately:

  • Elevate the dialogue around cannabis use disorder as a major public health issue. We must educate the public on the misconceptions about cannabis use, raise awareness about the signs of the disorder and improve access to treatment. Caron advocates that governments provide financial resources through taxation of the cannabis industry to support education, prevention and treatment for substance use disorders.
  • Tighten the list of conditions for which people are certified to use medicinal cannabis. The federal government and appropriate agencies must step in to begin researching medical claims and the effects of higher concentrations of THC on the brain, regulating the dose and usage of cannabis products. Current indications are simply too broad.
  • Intensify efforts to prevent teenage use. Cannabis should not be used by anyone under the age of 25 because the brain continues developing through age 25, and cannabis can permanently damage the brain as it develops. Every year we delay a person’s first use of cannabis results in a much lower risk of developing problem usage for cannabis and other substances. Heavy use of cannabis products by teens and young adults with mood disorders -- such as depression and bipolar disorder -- is also linked to an increased risk of self-harm, suicide attempts and death, according to a 2021 study in JAMA Pediatrics. An important side note is that we are seeing increasing instances of cannabis laced with fentanyl, a synthetic opioid up to 100 times more potent than heroin, which is causing an epidemic of overdoses and even fatalities.
  • Stop using cannabis as a treatment for opioid use disorder. Such use is not supported by medical research, and it has led to dangerous marketing practices by some cannabis companies. In Pennsylvania, physicians who recommend cannabis for medical use are required to register with the department of health.
  • Conduct more research on cannabis and its effects. Federal law still makes research on cannabis difficult. Those restrictions should be lifted. There are hundreds if not thousands of chemical compounds in cannabis, and some of those may indeed be medically useful, but without evidence-based guidance we are left to rely on anecdotal reports from people who say it has helped them. We need peer-reviewed, double-blind clinical studies to confirm this. We also need to continue research on exactly what factors play a role in leading people to develop a cannabis use disorder and a better understanding of cannabis’ relationship to the development of anxious, depressive, manic and psychotic symptoms.

If we continue towards the path of full legalization, we need to prepare ourselves to deal with the increase in problem usage. Far better would be to prevent the problems in the first place. To do that, we need strong education and prevention campaigns, significantly more research, better regulation and improved access to treatment for those who need it.

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