April 28 (Bloomberg) -- Marijuana in pill or spray form lessens painful spasms of multiple sclerosis, though it doesn’t appear to ease abnormal movements of other neurological disorders, a review of studies found.
There wasn’t enough information to find smoked marijuana to be effective, the analysis of 34 studies by the American Academy of Neurology concluded. Researchers also found no likely benefit from marijuana for patients with Parkinson’s disease, and insufficient evidence to say it helps patients with Tourette syndrome, epilepsy, Huntington’s disease or cervical dystonia.
The findings, published today in the journal Neurology, may help open communication between doctors and patients about medical marijuana use, said Barbara Koppel, the study’s lead author. This is especially important as marijuana laws across the country are liberalized and more patients seek to buy it on their own, many without consultation, she said.
“This guideline gives us an idea of who might benefit and what they should watch out for,” said Koppel, a professor of neurology at New York Medical College, in a phone interview. “Each patient has to look for a dose that they can tolerate and a formulation that they want to use.
In the U.S., 20 states and the District of Columbia have laws allowing doctors to use cannabis therapy. Two states, Colorado and Washington, allow for the legal production, sale and consumption of marijuana for non-medical purposes.
‘‘Even in areas it’s allowed to be prescribed, a lot of doctors don’t get involved,” Koppel said. “Politics is some of it, and I don’t think the regular medical community was aware of the so-called scientific use of it.”
The study is the second in a month from the academy to show benefits of medical marijuana use for MS symptoms. Findings published March 24 showed that among about a dozen alternative therapies only marijuana was found to be helpful in MS.
Today’s review found that oral cannabis extract in pill or spray form can lessen spasticity symptoms in the short term and ease central pain, also known as a “pins and needles” burning.
David Anderson, 64, was diagnosed with MS 20 years ago, and says the pins and needles feeling is why he would want to try medical marijuana as an alternative if it were available.
“I’ve read too many stories where it worked,” said Anderson, who lives in Madison, New Jersey and retired on disability from Merrill Lynch in 2004. “The traditional treatments don’t treat pain. They attempt to slow as much possible the progression of MS.”
The cannabis pills didn’t lessen tremor shaking or lessen urination and bladder control problems in MS patients, today’s research found. Oral marijuana spray, however, was found to probably help lessen frequent urination.
There was moderate evidence showing synthetic tetrahydrocannabinol, or THC, the main psychoactive ingredient in the cannabis plant, might also reduce spasticity symptoms and cramp-like pain and painful spasms.
“We have receptors in our brain and obviously this chemical is doing something, and it’s so hard to prove it,” Koppel said.
About 2.3 million people worldwide have MS, an autoimmune disease that can be difficult to diagnose. The disease destroy neurons when the immune system attacks the protective coating called myelin on nerve fibers, disrupting the body’s communications. The condition may lead to blurred vision, poor balance, tremors, speaking difficulties, fatigue and paralysis.
Researchers looked through more than 1,700 abstracts collected from the last 50 years on medical marijuana usage, narrowing them to 63 papers applicable to neurology. From that set, 34 met the criteria for inclusion in the study.
The sample size of many of the studies was not large enough to show precise evidence, Gary Gronseth, the co-author of the study and a professor at the University of Kansas Medical Center, said in a phone interview.
“We hope the message will come across that there’s a huge gap in the literature,” Gronseth said. “A lot more research needs to be done before this is used for most neurological conditions.”