Medical Marijuana, Legalization and Science: A Complicated Issue

Medical marijuana, and clinical medical marijuana have the same legal definition according to the Michigan “Medical Marihuana Act” of 2008. Medical marijuana is any part of the Cannabis sativa plant, or derived compounds from the plant, which have been prescribed by a qualified and registered primary care physician for the purposes of treating a medical condition. The patient must also be registered with and issued an identification card by the Michigan Department of Community Health.

In Michigan, medical marijuana may be used in anyway seen fit by the patient, but only 2.5oz of medical marijuana may be possessed by a card-carrying patient at any time, and a patient may have no more than twelve live plants, which must be grown in a locked location. Medical marijuana may be provided by either the registered primary care physician or through licensed Medical Marijuana dispensaries, although the legalities of dispensaries in Michigan is a complex issue

So, when did the “medical” get placed in front of marijuana?

The medicinal qualities of Cannabis sativa were first recorded in 2737 BCE when Chinese Emperor Shen Nung prescribed cannabis tea for conditions such as “rheumatism.”Today we would categorize common rheumatism as arthritis, a condition commonly treated with medical marijuana. There has been much research into a number of medical conditions for which Cannabis sativa, or purified compounds from the plant, might be used.

The uses of medical marijuana can be classified into two grossly simplistic categories: the central (working on the central nervous system) and the peripheral (those that treat problems anywhere else in the body). Medical marijuana therapy has been shown to positively affect a number of  “central” (e.g. anxiety, nausea, lack of appetite, epilepsy) and “peripheral” (arthritis, lupus, pain, Crohn’s disease) maladies, typically resulting in a better quality of life for those afflicted. Perhaps most exciting, one study suggested that autism may soon be added to this list.

Peter Gulick MD, oncologist and Associate Professor in the Department of Human Medicine at Michigan State University, states that while he cannot legally prescribe medical marijuana, he does often utilize Marinol (synthetic Tetrahydrocannabinol - THC) in his medical practice. “I [prescribe] Marinol plus advise medical marijuana for nausea, HIV wasting, neuropathy, and appetite stimulation if weight is down,” he says.

Gulick goes on to explain that recommending a treatment does not guarantee its effectiveness. “I believe for nausea, especially related to HIV, it does wonders. Also for HIV wasting it is a great supplement. For neuropathy and pain control it works on case-by-case basis.”

I asked Gulick if he would feel comfortable personally using medical marijuana if he were ever diagnosed with a condition for which marijuana might be a therapeutic option. “Yes, I would!” He said, “And would use it over a lot of other medications; especially pain medication.”

“Fantastic!” You might say, “pot is the new penicillin!”

Not so fast.  

Since the late 1970’s, the scientific community has been characterizing the effects of compounds derived from Cannabis sativa. The main compounds of interest are called “cannabinoids” and C. sativa contains over 60 of them. The most well-known, and well characterized, of the cannabinoids is Δ⁹-Tetrahydrocannabinol (THC), the primary psychoactive compound in C. sativa.

In 1985, research from Mishkin and Cabral found that in a mouse model of herpes infection, animals treated with THC had more severe herpes infections compared to animals that did not receive THC. This was only the first of many papers that would go on to show an exacerbation of an infectious diseases by THC treatment. In 2007, research conducted at MSU in the laboratory of Dr. Norbert Kaminski by Dr. John Buchweitz demonstrated that treatment with THC made influenza infection worse in mice.

Research into the effects of the central nervous system have shown that THC causes a reduction in communication between neurons.

The National Institutes of Drug Abuse (NIDA) published a summary of the effects of THC on the brain titled “What are marijuana's long-term effects on the brain?” In short, studies in rats and longitudinal studies in humans have shown use of marijuana is related to changes in the structures of the brain related to memory and, in humans, those people that used marijuana had lower scores on memory, processing speed, and “executive functions” (i.e. “thinking). These side effects are particularly prevalent in people that use marijuana during adolescence .

Dr. Norbert Kaminski, Ph.D. of MSU, is a distinguished professor  and has spent much of his career studying the effects of cannabinoids on the immune system.

I asked him about his thoughts concerning the known adverse effects of cannabinoid based therapies. “As a research scientist having been trained in pharmacology and toxicology, I am very much aware that virtually all therapeutic agents have both beneficial as well as adverse effects, depending on how they are used,” he said, “Also part of this same equation is the benefits to be achieved versus the risks.”

Medical marijuana is, then, like most drugs; as a therapeutic for certain illnesses it works very well, but when it is used for excessively long periods of time or when a person is susceptible to the negative effects of the drug, it can be hazardous. For comparison, opiate drugs (e.g. hydrocodone, codeine, and morphine) are some of the most powerful ant-nociceptive (pain killing) compounds used in modern medicine and are widely accepted as a therapeutic, but they are also known to be highly addictive and can lead to overdoses (over 20,000 cases/year since 2007 according to NIDA).

But, with all the emerging data concerning the medicinal potential of marijuana, why is there so much more information about negative effects?

The past 40 years of research have been based on the categorization of marijuana, and THC, as drugs of abuse. As a result, funding for research into the therapeutic potential of cannabinoids is near impossible to acquire. “From what I observed,” Dr. Kaminski had said, “obtaining funding for research projects that focused on the positive effects, or potential therapeutic effects, of THC and other cannabinoids has been quite challenging.  My sense is that the tide might be shifting a little in this respect but very slowly.”

Part of this shift in how cannabinoids are viewed is the result of technological advancement and cultural acceptance. “With respect specifically to cannabinoid research,” Dr. Kaminski had to say, “we have learned a tremendous amount concerning the mechanisms by which this class of molecules exert their biological effects.  Having this knowledge has made the therapeutic use of cannabinoids more acceptable by the general public, medical profession and regulatory agencies.”

If marijuana were to be removed as a Schedule 1 drug under federal law, you would think funding agencies would support research of marijuana and its derived compounds as a therapeutic instead of a just “drugs of abuse”.  

However, Dr. Kaminski, with his 30+ years of experience, foresees things differently, “In part due to a growing acceptance of medical marijuana around the country and in part due to shrinking resources for research, I believe that there is a strong likelihood that in the near future research focused on the health effects as well as basic biology of cannabinoid use may very well decrease.  Such a trend seems counterintuitive as one would expect that as more people use marijuana there would be more reason to pursue research on both the therapeutic benefits as well as adverse health outcomes of recreational use.  Having said that, if the overall perception is that marijuana use is safe, why invest resources in conducting research?”

This is a troubling prediction, because more targeted cannabinoid based therapeutics, without some of the associated side effects, could have significant therapeutic potential. Just like all therapies, the more research into them there is, the better they become. Without research into cannabinoids, might powerfully therapeutic drugs never be discovered, tested and brought safely to the people who might benefit from them?

This then brings us back to the initial question, is the concept of “medical marijuana” legalization scientifically substantiated?

The answer isn’t clear. It’s a mix of controversial data and interpretations of that data marred by opinions and agenda on both sides.

“Ending the U.S. government’s war on medical marijuana research” by Dr. John Hudak, Ph.D. and Grace Wallack of the Brookings Institute gives a comprehensive breakdown of the consequences of marijuana legalization and reclassification of marijuana to a Schedule II drug. In their paper, Wallack and Hudak, like Dr. Kaminski, support the claim that the lack of research into the therapeutic effects of cannabinoids is largely due to the Schedule I designation and the consequential difficulty of receiving funding for those therapeutic studies. What’s more, Wallack and Hudak stress that more research needs to be done one both sides, “Expanding research should be a cause championed by the most passionate pro-marijuana advocates as well as the most ardent drug warriors—and everyone in between.”