Separating Fact from Fiction in the Cannabis Debate

Conversations about cannabis policy are heating up. So it’s no surprise that we suddenly seem immersed in claims and counterclaims on a slew of topics related to cannabis use and regulation.

Cannabis causes schizophrenia. Cannabis regulation leads to increased traffic fatalities. These are just some of the examples that seem to pop up, again and again, in news articles and online. They sound true, perhaps because they are repeated so many times, and also because they are often said to be based on scientific evidence.

In the UK, the Telegraph even ran the following headline: “Cannabis as addictive as heroin, major new study finds.” On its surface, this claim reads as if it were backed by scientific evidence. But is it?

The International Centre for Science in Drug Policy has tasked itself with determining the strength of scientific support for such claims. Over the past year, we’ve been working diligently on scanning the news media and online conversations about cannabis to identify the most oft-repeated or high-profile claims—including the ones above—related to its use and regulation.

We narrowed the list down to 13 by reviewing media reports, government announcements, and monitoring online discussion on cannabis. We then performed comprehensive scientific reviews of all of the relevant peer-reviewed published research. As our new reports explain, we found that not one of the claims was strongly supported by scientific evidence.

For example, the science does not, in fact, suggest that cannabis is as addictive as heroin. Rather, cannabis dependence is estimated to occur in less than one in ten people who use cannabis across their entire lifetimes. Rates of lifetime dependence to heroin, by contrast, are about one in four.

Does cannabis use cause schizophrenia? While studies have shown that cannabis use is associated with schizophrenia, this is a very different claim. Scientists suggest that people at risk of schizophrenia might actually use cannabis to mitigate early symptoms of the condition, and that this is the reason for the association. The claim, then, confuses correlation with causation.

Furthermore, if cannabis use caused schizophrenia, we would presumably see changes in schizophrenia rates based on levels of cannabis use. But during a period when cannabis use increased fourfold in the UK (1970–2010), the incidence of schizophrenia remained essentially stable.

Does cannabis regulation lead to more traffic fatalities as a result of people driving while stoned? In Colorado, recreational cannabis use and possession was regulated in 2012. Since then, traffic fatality rates have been below the yearly average seen over the past decade (i.e., since 2002). Of course, we don’t know what kind of traffic fatality rates we’ll see in the coming years in Colorado and other places that have regulated cannabis. But at present, there isn’t any evidence to suggest that regulating cannabis will lead to more people involved in deadly car crashes.

These are only a few of the examples reviewed in the reports. The main conclusion is that, for the most part, the global conversation around cannabis policy is mired in unscientific claims. And that can have serious consequences for the effectiveness—and potential harms—of cannabis policies in many countries.

In Canada, for instance, a federal election is set for the fall, and cannabis regulation has been front and center, with the current conservative government frequently advocating for a “tough on crime” approach. Tellingly, the Canadian government’s production of anticannabis public service announcements recently drew the ire of the country’s main physician group, the Canadian Medical Association, which refused to endorse the so-called “educational campaign” because it believed the ads were serving political—rather than educational—goals.

In the United States and elsewhere, third-party advocacy groups continue to spread disinformation about cannabis. Kevin Sabet, director of Smart Approaches to Marijuana, an antiregulation group, stated on CNN that cannabis “is a drug that can result [in] serious, long-term consequences, like schizophrenia,” a claim that, as described above, is not backed by science.

The dangers of masquerading falsities about cannabis as scientific evidence are serious: if the general public and our policymakers can’t distinguish between what is true or false, how can we expect to develop effective, evidence-based approaches to control cannabis?

Our new reports will help to separate fact from fiction. Given the rapid movement on cannabis regulation that we’re witnessing across the world, and the upcoming United Nations General Assembly Special Session on Drugs, it’s more important than ever to make sure the truth about cannabis use and regulation is publicly available.

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Cannabis is a wonder drug and only called a drug because the government did so. The history of Cannabis reflects that it should never have been added as a drug. One movie started the whole thing. Hemp should never have been banned from being grown in the US . It was our major product and grown by Washington.

Unfortunately, this article do not mention one of the most important things about cannabis - possibility that THC from cannabis help with or even cure many cancers.

True; but I think their focus, #CannabisClaims, is to shoot down falsehoods, rather than praise the benefits.

I think this is really a valuable contribution – though I would also think it's reasonable to highlight, as Kevin Sabet does, that it's probably not a great idea if cannabis is marketed aggressively, in the way that tobacco used to be, 30 years ago. I'm convinced that criminalizing cannabis is not a great way to go, but I would like much more nuance on the alternatives, to be fully convinced that there is a good way to go.

On October 5th, 2012 I was struck by a car. It almost killed me. I never used to smoke marijuana. Since I was struck, I have been smoking it. There is all kinds of things it helps me with. I am not smoking it to "get high." There are many medical reasons I smoke it. I live in Ohio, where this November they have it on the ballot. You can GUARANTEE I will vote to legalize it here.

I wonder if this so called drug is illegal because its likely to make people visit their friends and sit and socialize instead of going out and spending a fortune on trying to dampen there feeling of frustration by drinking alcohol to extreme and smoking tobacco like a chimney.
Money is far more important then human life. I suppose the fashion industry will also suffer as people are becoming less interested in material things and more interested in understanding how to be happy.

Is legalisation of marijuana not just going to be reminiscent of the problems faced with smoking and drinking. Smoking was seen as fashionable and the health risks were only really notice later when lung cancer started to become a common side effect. The tests that they do on marijuana aren't going to be able to effectively test the long term effects of the drug. So we if it was legalised it could just put an increased strain on an already strained public health system.

I feel that this hand-waving dismissal of causal link between psychosis or schizophrenia is irresponsible. Adolescent psychosis clinics are overloaded with cases of patients that have been heavy pot smokers. For those in the mental care system the link is too strong to brush off.

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