It’s been a great summer for pot—or, wait, has it?
Three studies highlighting the drug’s potential to reduce domestic crime, lower the rates of opioid overdoses, and halt Alzheimer’s were waved like victory flags last week. It’s a 180-degree turn from weeks earlier when researchers out of Northwestern University allegedly found that casual marijuana use can damage the brain.
With 24 states in America where medical marijuana is legal, including two recreationally, the studies are part of a growing body of proof that the stigma surrounding marijuana is beginning to disappear. News organizations are suddenly hiring pot editors, networks are grooming weed correspondents, even The New York Times is running pot-themed ads.
What hasn’t come with cannabis’s headfirst dive into the mainstream, at least on the scientific front, is clarity on how the drug affects humans. One week it’s touted as a date-rape drug, the next it’s the answer to domestic violence. The mixed signals are endless. Does it cure Alzheimer’s or damage your brain? Stop cancer or cause it?
The unfortunate truth is that there is nowhere close to enough research on marijuana and its effect on humans to make definitive claims at this point. As long as marijuana remains on the schedule I substance list—which suggests that it has no medical value—there won’t be. None of these studies, campaigns, or assertions should be enough to sway public opinion towards or against pot. On the contrary, they should fuel a desire to loosen Congress’s tight hold on medical marijuana for testing. Without the freedom to test marijuana on humans, the vast majority of these studies center on speculation. Until that freedom is granted, these studies shouldn’t be used as vehicles to sway public opinion one way or the other. They aren’t sound enough to do so.
Take the three most recent studies as examples.
In the first, researchers from the University of Buffalo, Yale University, and Rutgers University studied 600 couples to analyze the impact of cannabis on domestic violence in the first nine years of marriage. Their results showed less frequent episodes of violence among married couples, both for men and women, with more frequent marijuana use. “Marijuana use did not increase the odds of any type of aggression,” the authors concluded. But their results, which didn’t control for other factors, show only correlation and not causation. And without a concrete way to measure the incidence of domestic violence, it is purely observational.
The second study, this one published in the American Journal of Medicine, analyzed the effect of medical marijuana on opioid analgesic overdoses in California, Oregon, and Washington. The results showed a 24 percent lower mean rate of opioid overdoses in state’s where medical marijuana is legal, versus states where it is not. While Mark Kleiman, a drug policy expert at University of California, Los Angeles calls the study “promising,” he believes it is far from proof that cannabis use could actually lower opioid overdoses. The study, which used state-driven data, didn’t specifically study medical marijuana users, as it implies. “They used the wrong data set,” says Kleiman.
The third study, a clinical analysis from the University of Southern Florida’s Health Byrd Alzheimer’s Institute, found that low levels of Tetrahydrocannabinol (THC, the psychoactive ingredient in marijuana) can slow or halt the progression of Alzheimer’s disease. This led to a rash of headlines that smoking marijuana could “stop” or “treat” Alzheimer’s. But, as Kevin Sabet from Project SAM (Safe Approaches to Marijuana) points out, no one referenced by this research was actually smoking marijuana, just ingesting THC. “We have known that small amounts of certain components of marijuana may have medicinal value,” Sabet says. “That is very different than saying today's high-grade high THC marijuana is good for Alzheimer's.”
Inflating the claims made by a marijuana study (which I have, admittedly, fallen victim to myself) isn’t exclusively a pro-legalizer move. Those on the other side of the aisle are guilty too.
The most recent example is a joint study from Northwestern and Harvard, in which researchers performed 3D scans on two sets of 20 students—one group that smoked cannabis, the other that did not. After comparing the two scans, scientists found two major differences in the brain makeup of those who smoked, leading many to assert that this proved “experimenting with cannabis” alone could damage the brain. Scientific America quickly deflated this with a short post pointing out holes in the research: One, the scans were only conducted once (ruling out a conclusion of causation); and two, cognitive performance was not measured afterwards (making the term “damage” a stretch).
In none of these four instances should the study have been interpreted as proof of what marijuana can or cannot do. Yet in all of them, that’s exactly what happened. In fairness, this is neither the researchers fault, nor the readers. With its classification as a schedule I substance, it is very difficult to gain federal approval to study it on humans—getting the federal government to agree to testing requires an implicit acknowledgement that its classification (defining it as having no-medical value) may be wrong.
Slightly more than a dozen researchers achieved this feat, and even when they do, it can be years before the research is carried out. Dr. Sue Sisley, whose five-year battle to test marijuana on veterans with PTSD was finally given a pass by the feds, was fired from the University of Arizona (where she was to perform the research) last month. Her research has been halted indefinitely.
Amanda Reiman, policy manager for the California branch of the Drug Policy Alliance, captures the complex research problem well. “Researchers can do pre-clinical research all day long. But if you really want to develop it into medicine that human beings can take the next step is human trials,” Reiman explains. “That is where the barrier comes up. When you try to get it rescheduled, the feds say you need evidence to do so. But how can you perform that evidence when you’re not allowed to test it?” she asks. “It’s a Catch-22.”
Kleiman, whose efforts heading up Washington state’s legalization reform earned him the unwelcome nickname “pot czar,” hopes people will exercise more caution when discussing these studies. “Everybody’s cherry-picking results. I don’t think there’s [any study] out there yet that would take the fair-minded person and say ‘That’s the killer result that will change my mind,’” he says. Both politicians and the media, by exaggerating the claims of only certain studies, are exacerbating the problem. “Oddly enough,” he says with cynicism. “There aren’t any studies that both want to report."