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Four Cannabis Myths

We know that humans have been using cannabis for medical, textile, and spiritual uses for a very long time. In fact, hemp cord found in pottery in the area of modern day Taiwan was dated at 10,000 BCE.

Agriculture is a fairly recent invention—the practice is only about 10,000 years old—and it is the basis for modern civilization. Carl Sagan, in 1977, suggested that cannabis might have been the first domesticated crop, and was possibly instrumental to the development of civilization itself. And, here in the U.S., cannabis was widely included in the pharmacopeia until the late 1930’s. Prior to cannabis prohibition, there were over 600 commercially sold medical products with cannabis as the active ingredient.

However, for the past 9 decades, cannabis prohibitionists have controlled the cannabis narrative and have disseminated misinformation about its effects. This campaign to discredit cannabis has created a powerful stigma against its use, partly by criminalizing cannabis users. The federal government stubbornly classifies cannabis as a Schedule I substance, despite long-standing evidence of its efficacy and safety.

The misinformation disseminated over the past 90 years remains very prevalent. So much so that many of our patients fear telling their doctor about their cannabis use, fear losing insurance benefits, and are embarrassed to tell their adult children. And of course, real dangers remain for cannabis users—from incarceration to the loss of public housing, grants, professional licenses, and employment.

Unfortunately, it’s not only the prohibitionists disseminating bad information. Underground remedies, the rapid development of new technologies and products, and easy access to information on the internet has helped to allow many cannabis myths and misconceptions to flourish. I’m going to talk about a few today.

Myth#1: Cannabis is highly addictive and can lead to harsher drugs. Or: The Gateway Theory.

We hear this gateway argument often from policy makers—it is one of the principal reasons cited in the defense of prohibition. Of course, this argument states that people who use cannabis are more likely to go on to use illicit drugs. So why is it flawed argument?

The first reason is logic. Cannabis is the most widely used and most widely available illegal substance in the world [1], so it stands to reason that a person who has used illicit drugs—such as cocaine or heroin—is more likely to have also used cannabis than someone who has not used any of these substances.

The second reason is that correlation does not demonstrate causation. Using the gateway logic, one could argue that drinking milk is a gateway to illicit drug use since most people who use illicit drugs also drank milk as young people.

Again, because cannabis is the most widely used illegal substance in the world—if the gateway theory were true—we would expect to see many more users of illicit substances. Most people who use cannabis do not go on to use illicit drugs.

And, evidence that directly contradicts the “gateway” theory is not difficult to find. In a study published in the Journal of School Health in 2016 [2], researchers wanted to help schools identify the first substance in the sequence leading to polydrug use—because of scarcity of funds schools want to determine how to fund substance use prevention programs.

They interviewed nearly 3000 U.S. 12th graders to determine the first substance that adolescents use. The answer: alcohol is the most commonly used substance, followed by tobacco.

I’ve met with addiction recovery patients who have told me that they believed cannabis was a gateway drug for them and there is no way to convince them otherwise. Addiction is a personal, individualized experience, and anything can be a trigger. But the facts remain: most people that use cannabis do not struggle with addiction problems and do not go on to use illicit substances.

But is cannabis highly addictive? The National Institute on Drug Abuse has an article on their website titled, “Is marijuana addictive?” in which they state, that, in 2015, 138,000 US adults voluntarily sought treatment for cannabis use [3]. The estimated number of US adults who tried cannabis by 2015 was about 33 million [4]. That’s .4%.

However, NIDA states that, because 4 million people in the US met the criteria for cannabis use disorder, the number of cannabis users with a dependency is about 9%, still well below alcohol and tobacco dependency rates.

The Benjamin Center for Public Policy Initiatives, in their 11-page essay, “The Marijuana Gateway Fallacy,” [5] concludes that, “There is compelling and enduring evidence that cannabis is not a gateway drug.”

In fact, in states where cannabis is legally accessible, there is a decrease in the use of controlled substances, and cannabis appears to be an exit substance rather than a gateway drug.

  • A study published in the Harm Reduction Journal in 2017 stated that the biological mechanisms of cannabis strongly suggest that cannabis can help address opioid addiction.[6]

  • A study published in Journal of Psychopharmacology in 2017 stated, out of 1500 patients surveyed, 76% reduced their opioid use after getting access to cannabis. Seventy-one percent reduced their use of anti-anxiety meds, 66% reduced their use of migraine meds, and 65% percent reduced their use of sleep medications.[7]

  • A clinical study done with 122 participants in Canada found that cannabis use is associated with reduced cravings for cocaine and opioids. [8]

So, the data demonstrates that cannabis is not highly addictive, and there is no good data to suggest that cannabis is a gateway drug. In fact, many patients use cannabis as an exit substance to wean themselves from addictive and dangerous pharmaceuticals.

Myth #2: Cannabis Lowers Intelligence

We can all imagine the stereotypical stoner. This stereotype has been reinforced for decades, not only by prohibitionists but also by popular culture, and it’s impossible to deny the impact of franchises like Cheech and Chong on the way the general public perceives cannabis users, especially when it comes to intelligence. And, of course, anti-cannabis campaigns in the 80’s taught us that cannabis kills your brain cells.

There’s actually good, peer-reviewed data available on this topic. To determine whether cannabis impacts IQ or inflicts cognitive harm, researchers started following large groups of teenagers over long periods of time, some of whom would eventually use cannabis and some of whom would not. Then they compared those two groups.

The first study, completed in 2012 reported significant declines in IQ in heavy cannabis users compared with those who used cannabis occasionally or not at all.

The results of this study were analyzed and reviewed by researchers at Duke University [9] and published in a respected journal. This became known as the Duke study, and it made headlines after claiming that persistent cannabis use was associated with a decline in cognitive abilities and that, even after stopping cannabis use, those abilities were never restored.

This study has had a major effect on how policy makers and dependence experts thought about the risks of early and heavy exposure to cannabis. This seemed like, finally, some data-driven science that prohibitionists and anti-cannabis legislators could point to for support of their draconian cannabis laws. That victory, however, was short-lived. Within days, the medical community began to point out that the Duke study was compromised by multiple flaws that resulted in skewed data.

For example, researchers who published a subsequent study [10] about 6 months later in the same journal pointed out that the Duke study failed to account for other factors that affect cognitive development, such as tobacco use, alcohol use, mental illness, socioeconomic status.

And while prominent members of the medical community, as well as expects in the field of drug abuse and addiction cast doubt on the veracity of the Duke study, that study did have one notable advocate: Dr. Nora Volkow, director of the National Institute on Drug Abuse. She told the Associated Press, “I think this is the cleanest study I’ve ever read.” [11]

Subsequent, peer-reviewed research came to a very different conclusion than the Duke study. The University College of London tracked more than 2,300 children from 1991 onward. They determined that there was “no relationship between cannabis use and lower IQ,” especially after adjusting for factors like nicotine use, alcohol use, and the education levels of the participants’ parents.

They did find, however, a correlation between tobacco and lowered IQ.

In 2015, researchers at the UCLA and at the University of Minnesota published a study that evaluated whether cannabis use was associated with changes in intellectual performance in twins. They tested participants for intelligence between ages nine to 12, before they had any involvement with cannabis, and again between ages 17 to 20.[12]

This was the largest ever longitudinal examination of cannabis use and IQ change. Investigators found no relationship between cannabis use and IQ decline. They also saw no significant differences in performance between cannabis-using subjects and their non-using twins.[13]

In 2017, a team from the UK and Wales published results from another study [14] that evaluated whether cannabis use is directly associated with the cognitive function in sets of twins. The authors concluded that, “Cannabis use in adolescence does not appear to cause IQ decline or impair executive functions, even when cannabis use reaches the level of dependence.”

The notion that using cannabis has lasting negative impacts on intelligence is a longstanding one, and it is a claim made by people on across the political spectrum. The science, however, finds no factual basis for this contention.

MYTH 3: Cannabis Legalization Is Linked to the Rise in Traffic Fatalities

This is obviously a public safety concern: if we legalize and normalize cannabis use, will there be more impaired drivers on the road and will that lead to more traffic fatalities?

We have heard alarming statistics about traffic fatality rates in legal states like Colorado and Washington. When you look closely at these statistics, you’ll see that they are mostly published by one group, The Rocky Mountain High Intensity Drug Trafficking Area group, a federally-funded law enforcement group with an admitted anti-cannabis bias. Its director, Tom Gorman, has publicly acknowledged that much of the data assembled by the their group is opinion-based. [15] What does that mean? It means they make some of it up.

So, what conclusions are drawn by organizations that actually study real traffic data?

  • A study published in the American Journal of Public Health in 2017 [16] found no significant increase of motor vehicle fatalities in Colorado and Washington State, where adult-use cannabis is legal, compared with eight states where it is not legal. All of the states that were compared have similar populations, vehicle ownership, and traffic laws.

  • In another study, researchers at Columbia University reported in 2016 that, “On average, medical-marijuana law states had lower traffic fatality rates than non-MML states.” [17]

  • And, this same study found that cannabis laws are especially associated with reductions in traffic fatalities among 25-44 year olds. The researchers assume the reduction is most likely due to its impact on alcohol consumption. Young men in legal cannabis states are drinking less alcohol.

Nobody is advocating for impaired driving. But this idea that legalizing cannabis leads to carnage on the highways is simply not borne out by facts.

MYTH #4: CBD is Medical and THC is Recreational

We often hear, especially at city council meetings, how people support medical cannabis use but do not support adult-use, or what is sometimes referred to as recreational cannabis use. Our at patients at Radicle Health use cannabis to treat symptoms related to serious conditions or disease—Parkinson’s, cancer, Crohn’s disease. Other patients use cannabis to treat less serious conditions but which can affect the quality of life—chronic pain, insomnia, anxiety and depression.

And some patients want to use cannabis simply because they want to improve their mood, be more communicative with their spouse, be more patient with their children, feel more creative, or laugh more.

These are all therapeutic uses for cannabis. They are all legitimate. Rather than creating this false dichotomy between adult-use and medical use, at Radicle Health we prefer to distinguish between use and misuse.

We can all understand the difference between having a glass of wine with dinner most nights and having a glass of wine with breakfast most mornings. Perhaps a better analogy would be having 2 cups of coffee in the morning versus having 2 pots of coffee in the morning. It’s no different with cannabis.

There are over 100 cannabinoids in cannabis. There are no good cannabinoids and there are no bad cannabinoids. Those that we’ve studied can all be used to effectively treat conditions and disease. For many conditions, you must use THC to achieve relief. The idea that THC is recreational is nonsense.

How is it that these myths and misconceptions about cannabis have such staying power that they have the ability to influence and inform our national policy? Why did the United States adopt cannabis policies that have produced so much misery and so few good results? We usually like to end these blogs on a positive note, but before we can do that, we first have to say something about Richard Nixon.

The US has been criminalizing psychoactive substances since San Francisco’s anti-opium law of 1875, but it was Richard Nixon who declared the first “war on drugs.”

In 1994, Richard Nixon’s former domestic policy chief John Ehrlichman gave a very candid interview to Harper’s magazine, where he stated that, in the Nixon administration, there was a conscious and deliberate reaction to the anti-government and anti-war organizers. Ehrlichman said that criminalizing cannabis and illicit drug use—then associating these substances with political enemies—gave the Nixon administration a tool to disrupt these movements.

Erlichman stated that the U.S. couldn’t make it illegal to be black or to be against the war, but, “We could arrest their leaders, raid their homes, break up their meetings, and vilify them night after night on the evening news. Did we know we were lying about the drugs? Of course we did.” [18]

Here’s the good news: we are now living in an age when we have immensely powerful research tools at our disposal, and it is much more difficult to sustain those lies today. Please, do your own research. Take the scientific approach, which is skepticism and openness to thoughtful ideas, and use the resources available to you to learn more about cannabis, its safety, and its efficacy.

*This blog was inspired by Paul Armentano, who is the Deputy Director of Norml. Paul is a prolific writer and researcher of cannabis and cannabis policy. We encourage you to find his work and see him speak, when you have an opportunity.


  1. United Nations Office on Drugs and Crime, “World Drug Report, 2016,”





  6. “Rationale for cannabis-based interventions in the opioid overdose crisis, Harm Reduction Journal,” 2017,

  7. “Substitution of medical cannabis for pharmaceutical agents for pain, anxiety, and sleep,” Journal of Psychopharmacology, 2017,

  8. “Intentional cannabis use to reduce crack cocaine in a Canadian setting: A longitudinal analysis, Addictive Behaviors,” 2017,











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