Researching the Health Effects of Marijuana

Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

Why is there such a “dearth of rigorous research on the effects of marijuana”? The first major study wasn’t published until 2007. “Why did it take so long?…Why did the pharmaceutical industry fail to show any interest? Some might prefer a simple answer; since [it’s] just [a plant], it can[’t] be patented [for your stockholders], thus removing any incentive for investing…corporate funds.” Yes, but it’s more complicated than just that.

There are research funds available—a hundred million dollars of public money in a single year—but, historically, that money was generally “obtainable only for research on the negative effects.” See, in the U.S., cannabis is still officially lumped in with heroin as “a Schedule I drug”—which means, by definition, it’s classified by the government to have no medicinal value, a designation that “resulted in a near-cessation of scientific research, particularly” since the only way researchers could get it without risking jail time is a state-run farm in Mississippi, controlled by the National Institute on Drug Abuse, which has historically only greenlighted research aimed at “demonstrating…harmful effects.”

“Residents of 23…states can” walk out and just buy it, “but US scientists must wade through onerous paperwork,” and even when they do get it, it’s the wrong stuff; it’s not what people are actually using these days. The studies coming out are on like your grandma’s grass, a few percent THC, whereas the stuff available these days may be ten times more potent.

So, there’s like this crazy “catch-22 [where] the cannabis that should be studied…is illegal and the cannabis that can be legally studied—the decades-old Mississippi strain—is essentially kept off-limits.” So, “[i]ll-informed practitioners are thus left to make do with” like, anecdotes off the internet, like everybody else, which is bad medicine.

“As long as clinical research on cannabis is controlled by regulators expressly opposed to” the stuff, we miss out on the potential benefits. That’s no excuse, though. Just because there are “[p]olitical barriers” to research doesn’t mean we should lower our bar in terms of demanding evidence. “The sick still need medically sound treatments.”

Of course, now there’s pressure coming from both sides. The marijuana industry is now big business, and with those billions, can rally the troops. “Cannabis researchers already talk of being bombarded with e­mails from pro­-cannabis groups if they [dare] make [any] negative comments about the drug. ‘Marijuana research is like tobacco research in the ’60s,’ says [one University of Colorado researcher].” So now, there’s fear big money will push the pendulum too far the other way.

But the barriers go beyond money, and politics, and prejudice. Cannabis research is hard to do. I mean, how do you do a double-blind study with marijuana? People know when they’ve been duped with placebo dope. People can tell the difference between pot brownies and regular brownies; otherwise, they wouldn’t eat them. And so, if you know you’re getting the active drug, the placebo effect can kick in hard, notes one neurobiology researcher, especially when you’re dealing with subjective outcomes, like pain or mood.

And, imagine if you’re trying to do a population study on memory or cognitive impairment, and you’re asking heavy pot smokers to try to remember how much they’ve been smoking over their life. I mean, you can imagine how that might “influence data accuracy.”

Let me give you an example of how convoluted this can get. Neuropsychological testing of cannabis users have found residual negative effects, in terms of scoring slightly lower on memory tests. But how do we know it’s not a matter of motivation, rather than actual cognitive impairment? That had never been tested, until this study. They gave a group of potheads a standard learning test and just gave the standard shpiel, you know: “Please complete the following series of tasks which measure different areas of cognition, like memory and attention.” That’s what you’d normally say, and when you do, pot smokers score significantly worse. Ah, but what if you instead said this: “Please complete the following series of tasks… It is important that you try your very best on these tasks, because this research will be used to support legislation on marijuana policy.” So, hey, if you do good, they might decriminalize weed or something. And, under those circumstances, boom: the apparent cognitive impairment disappears.

Now, you could argue that lack of motivation is a problem in and of itself. But, hey, it’s better than having long-term brain damage.

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Image credit: BRICK 101 via Flickr. Image has been modified.

Motion graphics by Avocado Video.

• brain health
• cannabis
• cognition
• industry influence
• marijuana
• memory
• placebo effect
• smoking
• tobacco