Why we know so little about cannabis – and why scientists are worried

As we have reported on the science of cannabis in recent weeks, nearly every researcher we spoke to lamented the yawning gap in our understanding of the drug’s effects on our health, the environment, society and much more. So why, given our long history with the drug, are there so many unanswered questions?

Research into cannabis really only started in earnest two decades ago. It picked up steam in the late 1990s and early 2000s, beginning with studies showing that marijuana could reduce nausea in people with HIV and in those undergoing chemotherapy. Since then, the field has exploded.

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Yet the number of published studies about cannabis pales in comparison to the trove of data we have on drugs like tobacco and alcohol.

“We don’t have foundational data on cannabis that we have for other stuff,” says Ryan Sultan at Columbia University in New York.

A big reason for this is that government regulations have made it exceedingly difficult to study the drug. In the US, for instance, researchers must obtain a special licence from the Drug Enforcement Administration, and they can only study cannabis grown at licensed facilities – prior to 2021, there was just one of these. Even in Canada, where recreational cannabis use has been legal since 2018, federal and provincial restrictions have encumbered research.

While things are starting to change, we have reached a place where the availability of and hype around cannabis products has outpaced actual evidence of their effects. That has people like Sultan worried. “The whole treatment and medicinal thing I find very aggravating,” he says. We don’t know what doses are appropriate, what their long-term effects are or even what people are consuming, he says. “In fact, we know the things they’re getting are not what the label says they are. So how could you even do dosing recommendations when you don’t even have accurate ways of deciphering [what’s in it]?”

There are many fundamentals we have not yet got to grips with, from the way that the endocannabinoid system can influence our health to understanding how the cannabis products that are readily available to the public today are both produced and consumed, which can look very different to the controlled settings of most of the studies we currently rely on for insights. “Let’s find out what we need to find out so that we can do this in a thoughtful, intelligent way as opposed to what I feel like we’re doing, which is just running a natural experiment,” says Sultan.

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