Image source: Pixabay.

It's an ailment that often flies under the radar, but it costs employers $13 billion in lost productivity and workers 113 million in lost work days each year. It's also the world's eighth most disabling disease and affects 38 million men, women, and children in the United States. Despite these eye-popping facts, courtesy of the Migraine Research Foundation, migraine headaches remain very much a mystery to researchers.

This isn't to say solutions aren't in the works for migraine sufferers. There are medications on pharmacy and over-the-counter shelves designed to alleviate migraine symptoms, as well as therapies being developed by drugmakers right now that are attempting to tackle the disease. But when push comes to shove, there is no cure for what migraine sufferers go through when an episode, which can last anywhere from four to 72 hours, strikes. It means the search for a breakthrough medicine continues.

Is this illegal drug the answer to curbing migraine headaches?
However, as published in the journal Pharmacotherapy earlier this month, and via the National Institutes of Health's online library of medicine, four researchers in Colorado believe they may have found another potentially effective treatment for migraines. The catch? This treatment involves the use of a currently illegal drug: marijuana.

Image source: Pixabay.

Researchers from the University of Colorado Anschutz Medical Campus and Gedde Whole Health used two medical marijuana specialty clinics in Colorado to test 121 patients with a primary diagnosis of migraine headaches between January 2010 and September 2014. The idea was to determine what effect, if any, marijuana had on reducing migraine frequency over the course of the month with the assumption that cannabinoids within the cannabis plant could positively affect serotonin production and reduce the severity of, or completely eliminate, a migraine. Prior research has suggested a connection between low serotonin levels and migraine frequency.

The results demonstrated a statistically significant advantage for marijuana when it came to migraine frequency reduction. Migraine frequency for the tested patients dropped from 10.4 per month to just 4.6 per month, a 56% clinical benefit. The study notes that most patients used more than one form of marijuana, and positive effects were noted in 48 patients, or roughly 40%. This included 14 patients who were able to abort their migraine headache completely. Additionally, inhaled marijuana was the most common use method attributed to aborted migraine headaches.

Conversely, 14 patients, or about 12%, reported negative effects during the study, which included somnolence (i.e., a state of extreme drowsiness) and difficulty in controlling the effects of marijuana based on the timing and intensity of the dose. Most of the negative effects of the study were tied to marijuana edibles.

Ultimately, researchers concluded that the statistically significant result merits further research. No causation can be determined just yet, but it's an interesting and encouraging start for marijuana as it relates to migraine research.

Image source: GW Pharmaceuticals.

Marijuana notches another clinical victory
This isn't marijuana's first positive result in clinical studies, either.

In May 2013, an abstract study published in The American Journal of Medicine looked at more than 4,600 adults, 579 of which were current marijuana users, and 1,975 which have previously used marijuana. It showed that current marijuana use was tied to a 16% reduction in fasting in insulin levels and a 17% reduction on HOMA-IR, which is associated with insulin resistance. The takeaway is that marijuana could be potentially effective in treating type 2 diabetes by promoting improved glycemic balance.

More recently, a study was published in the Journal of Leukocyte Biology from researchers at the University of South Carolina School of Medicine, which showed that the cannabinoid THC may lengthen the time it takes for incompatible organs to be rejected by a patient. Keep in mind that this study was conducted on mice and not humans, but there was a noted delay in rejection for the mice given THC compared to the placebo.

Even publicly traded drug developers are getting in on the act. GW Pharmaceuticals (NASDAQ:GWPH), which has discovered more than five dozen cannabinoids and develops therapies that work with the cannabinoid receptor system found within our bodies, is working on a potentially groundbreaking treatment for two rare types of childhood-onset epilepsy. In clinical studies, GW Pharmaceuticals' Epidiolex, a cannabinol-based drug, reduced seizure frequency by more than 50% for Lennox-Gastaut and Dravet syndrome patients.

This represents just a handful of the benefits marijuana has demonstrated in prior clinical studies.

Image source: Flickr user Ron Cogswell.

Don't rock the boat
Despite the momentum for marijuana on the medical front, and within individual states -- marijuana is now approved for medicinal use in 23 states, and for recreational adult use in four states -- the drug still appears to have a cloudy future with investors.

Looking at the basics, marijuana legislation is currently stymied at the federal level, and it looks to remain this way for the foreseeable future. We've entered an election year, and most politicians would prefer not to stir the pot (pun fully intended) before we head to the voting booths.

More importantly, though, lawmakers don't believe they have a broad enough safety profile for marijuana as of yet. President Obama has suggested that as more states legalize the drug it'll coerce Congress to act, but I just don't see this happening until we have longer-term studies on marijuana easily accessible by lawmakers. With little incentive to act at the moment, Congress is likely to stymie any attempts at marijuana legislation at the federal level.

This inaction bodes poorly for marijuana businesses on all levels. Businesses that deal primarily in the sale of an illegal drug aren't allowed to take normal business deductions, and their access to basic banking services is extremely limited. Any chance these businesses and the marijuana industry has of flourishing is being capped by the inactions of the federal government.

Could things change? It's always possible, but I certainly wouldn't guarantee it. As such, even with exciting developments in medical marijuana research, and recreational marijuana blazing ahead, I would opine that marijuana remains a hands-off investment for the time being.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.