Say What? 2 New Studies Find Little Evidence That Marijuana Helps Treat Chronic Pain and PTSD

When it comes to growth industries, essentially nothing tops legal marijuana. According to cannabis research firm ArcView, the legal cannabis market in North America is slated to grow from $6.9 billion in 2016 to an estimated $21.6 billion by 2021 -- a 26% compound annual growth rate.

This growth is possible because the American public's aggregate opinion on pot has rapidly shifted over the past two decades. Back in 1995, national pollster Gallup found that only 25% of respondents wanted to see marijuana legal across the United States. However, by 2016, this had increased to an all-time record high of 60%.

What's more, a separate study released by Quinnipiac University in April 2017 found that an overwhelming 94% of respondents favored the national legalization of medical cannabis. Given this latter support figure, it's probably not as shocking that 29 of 50 states have legalized medical marijuana since 1996.

But what if medical cannabis isn't all it's been touted to be?

Medical marijuana: No shining star in treating chronic pain and PTSD?

According to two similar, but separate, publications in the Annals of Internal Medicine this August, medical cannabis has had few, if any, concretely positive impacts in treating chronic pain and post-traumatic stress disorder (PTSD).

One study, involving nearly a dozen authors, examined the impact that medical cannabis had on treating chronic pain, which is one of the most commonly prescribed indications. After analyzing data from 27 chronic-pain trials, researchers found only minimal evidence that medical weed was effective in alleviating neuropathic pain, and insufficient evidence that it relieved or alleviated pain in other patient populations.

And that's not all. After completing 11 systematic reviews and 32 primary studies, the nearly one-dozen researchers found that using medical cannabis led to an increased risk of motor vehicle accidents, psychotic symptoms, and short-term cognitive impairment. In other words, this group found that medical marijuana appears to be doing more harm than good.

A second study, published the same day by the same group of authors, examined the effectiveness of medical cannabis in treating PTSD. In a nutshell, the researchers found that the study evidence examined was insufficient to draw any benefit or risk conclusions given that no randomized trials were found. Further, the studies were deemed to have a medium-to-high risk of bias, and observational studies found no benefit of cannabis use for PTSD patients.

While the usual rules for published studies apply (i.e., that no concrete conclusions can be reached one way or another without additional research), there's also real-world evidence that cannabis or cannabinoids derived from the cannabis plant may not effectively treat pain.

GW Pharmaceuticals (NASDAQ: GWPH), the largest marijuana stock by market cap, and a company that's really excelled in recent years on the heels of clinical results from experimental cannabidiol-based drug Epidiolex for two rare types of childhood-onset epilepsy, has tasted failure in treating cancer pain before. Sativex, the company's only approved drug in more than a dozen markets outside the U.S. (Sativex isn't approved in the U.S.), failed miserably in a late-stage study in the U.S. examining its use in treating cancer pain back in 2015. Put plainly, cannabinoids and cannabis don't appear to be a guaranteed cure for pain.

Red tape makes answering this question a challenge

Then again, at the opposite end of the spectrum are more than a handful of studies that have suggested cannabis can treat chronic pain and a host of other disorders and ailments. There's also a recent study that shows, when given the choice, 92% of chronic pain sufferers prefer medical marijuana to opioids when treating chronic pain. Considering that more than 20,000 people died from opioid-related overdoses in 2015, cannabis provides a potentially safer and intriguing alternative. By comparison, no one died from a marijuana overdose in 2015 (or 2016).

What's stopping drugmakers and researchers from running studies that lawmakers could use to make real-world decisions on the benefit-versus-risk profile of cannabis? Look no further than the drug's current scheduling.

At the federal level, marijuana remains a schedule I substance, which means it has no medical benefits and is entirely illegal, like LSD and heroin. Because it's a schedule I drug, getting permission to run clinical studies is exceptionally difficult. In fact, there's currently just one federally permitted cannabis grow farm for medical research in Mississippi. And according to scientists via PBS, that grow farm has been producing moldy samples amid a lack of federal testing standards at the site.  In other words, red tape is holding back any opportunity for scientists to see if medical cannabis has the benefits that have been suggested in treating chronic pain, PTSD, and other diseases.

How does this red tape get lifted? That's really anyone's guess at this point. President Donald Trump has previously aligned himself with the public in that he supports medical cannabis. However, his Attorney General Jeff Sessions is a huge opponent of marijuana and would likely fight tooth and nail against easing testing restrictions. It's possible lawmakers could be coerced into action by voters who could push dissenters out of office come election time, but it remains to be seen if a single issue like marijuana could hold enough weight to push politicians out of office.

For the time being, there's a case that can be made from both sides of the aisle, and that's not good for the U.S. medical marijuana industry, nor is it good news for investors. Until we see meaningful change in Washington, there's little for the industry, or marijuana stock investors, to buzz about.

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Sean Williams has no position in any stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. The Motley Fool has a disclosure policy.