Study Finds Little Evidence That Medical Marijuana Helps Many Illnesses

Posted: Jun 23, 2015 4:05 PM

In the debate over whether marijuana should be legal, for both medicinal and recreational purposes, one thing both sides seem to agree on is that more research needs to be conducted. Thus, advocates and opponents should take note of several articles published Tuesday in the Journal of the American Medical Association related to medical marijuana. One analysis of note found there is little evidence from nearly 80 studies that the drug helps many of the illnesses for which it has been approved. 

Medical marijuana has not been proven to work for many illnesses that state laws have approved it for, according to the first comprehensive analysis of research on its potential benefits.

The strongest evidence is for chronic pain and for muscle stiffness in multiple sclerosis, according to the review, which evaluated 79 studies involving more than 6,000 patients. Evidence was weak for many other conditions, including anxiety, sleep disorders, and Tourette's syndrome and the authors recommend more research.

The analysis is among several medical marijuana articles published Tuesday in the Journal of the American Medical Association. […]

The researchers pooled results from studies that tested marijuana against placebos, usual care or no treatment. That's the most rigorous kind of research but many studies found no conclusive evidence of any benefit. Side effects were common and included dizziness, dry mouth and sleepiness. A less extensive research review in the journal found similar results.

It's possible medical marijuana could have widespread benefits, but strong evidence from high-quality studies is lacking, authors of both articles say.

"It's not a wonder drug but it certainly has some potential," said Dr. Robert Wolff, a co-author and researcher with Kleijnen Systematic Reviews Ltd., reports the Associated Press.

In an editorial in the journal, two Yale University psychiatrists suggested that widespread use should wait for better research to come out. Medical marijuana laws are on the books in 23 states and D.C. and the editorial’s authors say approval in many cases has been based on ‘poor quality studies, patients’ testimonials, or other nonscientific evidence.’

Researchers are optimistic that they'll soon "start to get a good science base" for marijuana's potential medical uses, according to the AP. Colorado, for example, which has approved marijuana for recreational use, has pledged millions in state funds for studies on marijuana’s potential medical benefits. 

Time will soon tell.