Marijuana: A user’s guide to the good, the bad and the ugly
Part 1: The good
By: Katherine Hill
Edited by: Sienna Schaeffer
Thirty years ago marijuana was the boogeyman of polite society. Nancy Reagan and parents across the United States warned children to “Just Say No.” Since then, marijuana’s image has undergone a remarkable rehabilitation.Today many Americans consider marijuana relatively benign at worst, or at best a possible cure for everything from cancer to glaucoma.
The whiplash in public opinion and deluge of conflicting media coverage has understandably left many people with more questions than answers when it comes to marijuana: Is it safe? Should I use it? Will it help my anxiety? Will it cause me to vomit uncontrollably for hours or days at a time?
Unfortunately, because marijuana is one of the most strictly regulated drugs in the country, little high-quality research has been performed on most claims related to pot, be they good or bad. Research is likely to increase now that both laws and public opinion are beginning to thaw, but it will be years before results from any large studies will be available.
For those of you who have plans for the next weekend rather than the next decade, this three part series will answer these questions and others by taking an unbiased look at what current scientific evidence says about the good, the bad and the just plain ugly of marijuana use.
The Good
This month we will be examining claims made about the possible benefits of smoking marijuana. As we dive into this section, try to keep in mind this time-tested medical truism: “cure alls cure nothing.” *
Throughout history it has been common for different “miracle cures” to fall into (and out) of public favor. Proponents claim that these treatments could cure a wide variety of ailments that seemingly had nothing to do with one another.
Past favorites include mercury, blood-letting, lobotomies, and cocaine. The only thing all of these treatments have in common that they will cure exactly zero medical ailments and will probably cause some new ones.
In recent years various parties have claimed that pot can do everything from preventing skin cancer to treating depression to preventing rejection after organ transplants. In fact, the supposed benefits are so numerous that we will only be able to address a small number of them in this article.
It is entirely possible that marijuana has one or even several of the benefits that are often attributed to it. However, according to history and common sense, it is considerably less probable that pot is some sort of miracle drug that fights cancer, cures depression, makes your teeth whiter and improves your posture all at the same time.
Nausea
We begin with nausea. The claim that marijuana can alleviate nausea is actually well supported. Fairly extensive studies in animals have shown that several compounds found in cannabis can reduce vomiting in animals that can vomit, like cats and pigeons, and reduce the gag reflex in animals that cannot vomit, like mice and rats.
Studies performed in (human) chemotherapy patients have found similar results. THC, one of the most well-known compounds in cannabis, is actually available in an FDA-approved pill form to treat the nausea caused by chemotherapy.
The pill, which is sold under the brand name Marinol, has the advantages of not making users high and of being legal in all 50 states. Purely anecdotally some patients have found that marijuana is more effective at treating nausea than Marinol. Some experts have suggested that this may be because marijuana reaches the brain more efficiently when smoked than when taken as a pill or because marijuana contains compounds other than THC that help fight nausea or anxiety.
Pain
Another popular claim is that cannabis is therapeutic for chronic pain. In terms of evidence, this claim comes in second place behind nausea in terms of scientific support. That’s not to say the evidence is great, just that the evidence for everything else is pretty terrible.
A review published in the Journal of the American Medical Association (JAMA) was able to identify 28 placebo-controlled randomized studies that examined the effect that several compounds found in cannabis have on chronic pain.
Placebo-controlled randomized trials are generally considered the “gold standard” of medical trials, but many of them are not perfect. In this case, the authors of the review concluded that only two of the trials were at a low risk for producing biased results, while 17 had a high risk of bias.
Despite the low quality of many of the studies, the authors concluded that there was moderate evidence that marijuana is effective at treating chronic pain. Other researchers have since disputed this analysis. They argue that the JAMA team misinterpreted their own data and that the evidence for marijuana as a treatment for chronic pain is weak at best.
Epilepsy
In the past several years a number of emotional and compelling videos have begun circulating about people who were “cured” of epilepsy by using marijuana.
At this point in time essentially all of the evidence for marijuana as a treatment for epilepsy is completely anecdotal. Anecdotal is essentially a fancy way of saying “some guy told me it worked for him.” Although these stories are often extremely compelling, they are pretty useless from a scientific point of view.
Maybe “some guy” was lying. Maybe he wasn’t lying but was himself duped by the placebo effect. Maybe he switched shampoo brands at around the same time he started taking marijuana and that’s the real reason he stopped having seizures. Maybe he just randomly stopped having seizures around the time that he started using marijuana but the one thing didn’t have anything to do with the other because the world is big and confusing and random and as much as we try to protect ourselves from the chaos sometimes things just happen for no apparent reason.
Now that we’re finished with that existential crisis, we can move on to examining what scant scientific evidence actually exists. Some studies have found that THC and CBD, two compounds in cannabis, have weak anti-seizure properties in animals.
Unfortunately, no study has ever replicated this study in humans. Researchers writing for the Cochrane Library were only able to find four randomized controlled trials that had ever tested the compound CBD as a treatment for epilepsy in humans.
All four studies were very small (under 15 participants) and were considered low-quality. As a kicker, none actually took data on whether the CBD decreased seizures; only on whether patients experienced any side effects.
The Cochrane researchers concluded, and I have to agree, that there is currently no evidence one way or another for cannabis as a treatment for seizures.
Cancer
Online, It is easy to find articles and websites that declare that it is possible to cure cancer using marijuana. The science on this is a little bit complicated, but I want to make clear up-front that there is absolutely no reason to believe that smoking a joint will either prevent or cure cancer. In fact, as I will explain in Part Two of this series, there is pretty good evidence that marijuana can cause cancer.
The claim that cannabis cures cancer really deserves its own article, but in the simplest terms the science has to do with receptors. Marijuana works by triggering little proteins called cannabinoid receptors in your brain.
These receptors are found in many different types of cells, including cancer cells. Some research has found that using compounds found in marijuana to trigger the cannabinoid receptors in some types of cancer cells (mostly gliomas and skin cancers) causes more cancer cells to to die than would otherwise be expected.
Most of this research has been performed on cells in petri dishes, a type of experiment that is notorious for yielding results that don’t hold up once scientists move into complex organisms. One major problem is that almost anything will kill cells in a petri dish. Frankly, keeping cells alive in a petri dish is generally much more difficult than killing them.
In fairness, some research has been performed in animals. Most of these studies have found that certain cannabis compounds have anti-tumor effects. Although animal research is somewhat more dependable than cells in a petri dish, it is important to keep in mind that it is still a big jump from a mouse to a human.
A few studies have also found that cannabis compounds can actually promote cancer, so that’s fun. While these results seem to be in the minority, it is important not to dismiss them offhand.
If a cannabis compound-based treatment is ever ready for prime-time, which is a big if, it will not involve anyone smoking a joint to cure their cancer. Researchers will need to develop a much more efficient way to make sure the compound of interest (and none of the carcinogens found in marijuana) is delivered to the correct part of the body.
Additionally, even if everything from here on out goes as well as possible, research will not lead to a full cancer “cure” in the traditional sense. I can say this for certain partially because many cancer patients currently use cannabis to fight nausea from chemotherapy. If there had been a rash of miracle cures someone would have noticed by now.
Even more importantly, cancer is an incredibly complex family of diseases that is notoriously difficult to treat. Scientists have learned the hard way that there is no such thing as a magic bullet. More likely is that, if cannabis-based compounds are shown to be effective, they will be given only to some patients who have specific kinds of cancers and only as one part of a multidrug treatment plan.
For now, I cannot stress enough that patients with cancer should take medical advice from their physicians, not from people on the internet hawking marijuana/crystals/whatever as a cure.
So What?
So what’s the takeaway from all this? Number one is to talk to your physician about any serious medical condition you may have and any treatment options you may be considering, rather than getting advice on the internet.** I do not wish to disparage the fine people at Leafly.com, but your physician spent a significant chunk of their life in school just so they would have the knowledge and experience to help you make the right decisions about your health.
At this point there is fairly solid evidence that cannabis can treat nausea. The evidence is considerably weaker or even nonexistent for chronic pain, epilepsy and cancer. It is possible that future studies will show that marijuana is an effective treatment for one or all of these conditions, but at this point I wouldn’t bet the farm on it.
To bring us back to where this all started: cure alls cure nothing. Or more accurately in this case, cure alls may cure a few things but they certainly are not magic bullets and will not fix dozens of ailments that have plagued mankind for thousands of years.
Join us next month when we dive into the dark side of marijuana use.
*Full disclosure: I stole this line from the podcast Sawbones.
**And yes, I am including this article in the “advice you get on the internet” category.
References
- Gloss, D. & Vickrey, B. Cannabinoids for epilepsy. Cochrane Database of Systematic Reviews (2014). doi:10.1002/14651858.CD009270.pub
- Kansagara, D. et al. Benefits and Harms of Cannabis in Chronic Pain or Post-traumatic Stress Disorder: A Systematic Review. (Department of Veterans Affairs, 2017).
- Kuhn, C., Swartzwelder, S. & Wilson, W. Buzzed: The Straight Facts about the Most Used and Abused Drugs from Alcohol to Ecstasy. (W. W. Norton & Company, 2014).
- Parker, L. A., Rock, E. M. & Limebeer, C. L. Regulation of nausea and vomiting by cannabinoids. Br J Pharmacol 163, 1411–1422 (2011).
- Velasco, G., Sánchez, C. & Guzmán, M. Towards the use of cannabinoids as antitumour agents. Nat Rev Cancer 12, 436–444 (2012).
- Whiting, P. F. et al. Cannabinoids for Medical Use: A Systematic Review and Meta-analysis. JAMA 313, 2456–2473 (2015).
