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"Spasticity is a major problem [in multiple sclerosis]," explained study author Dr. Jody Corey-Bloom, director of the University of California, San Diego Multiple Sclerosis Center. "People get very tight and it hurts, it feels like charley horses."
Medicines are available, but they don't help everyone, she added.
In the study, Corey-Bloom and her colleagues looked at 30 multiple sclerosis patients with muscle tightness who weren't helped by conventional medicines, and discovered they found relief by smoking pot. "Smoking pot reduces the spasticity by about a third compared to patients on [an inactive] placebo," she said.
The study is published in the May 14 issue of the CMAJ (Canadian Medical Association Journal).
More than 400,000 people in the United States have multiple sclerosis, or MS, a chronic, often disabling disease that attacks the central nervous system, according to the National Multiple Sclerosis Society. Symptoms can be mild, such as numbness, or much more severe, such as paralysis and vision loss.
Experts don't know the cause of multiple sclerosis. Research is focusing on the immune system, genetics and other factors.
Over the years, Corey-Bloom had heard some of her patients who smoked pot tell her it helped ease the symptoms of their disease, but she was skeptical. Research in medical literature was mostly on cannabinoids given orally, she said. And the studies tended to rely on subjective measures, just asking the patients if their symptoms improved.
So, she decided to do some research using smoked cannabis.
The average age of the 30 adults studied was about 50 years. Two-thirds needed walking aids, and one-fifth used wheelchairs.
Corey-Bloom randomly assigned the men and women to smoke either marijuana or a placebo joint once daily for three days. They did so in a special, well-ventilated research room.
After an 11-day "washout" period, the men and women returned for another session. Again, they smoked either the marijuana or a placebo once daily for three days. This time, they were assigned to the opposite group.
Before and after each session, the researchers measured the participants' muscle stiffness using an accepted scale. They also evaluated pain levels, tested certain thinking skills and looked at fatigue levels.
On average, the patients had about a three-point reduction on the spasticity scale. "It's a modest effect," said Corey-Bloom.
"It also reduced the patients' perception of pain," she added. Pain scores showed a 50 percent decrease in perceived pain.
Downsides included increased fatigue, she said. Cognitive (thinking) skills also declined in the pot-smoking participants. "There were some short-term, modest effects on cognition -- primarily attention and concentration," she noted.
The pot probably works, she said, by acting on special receptors in the brain involved in controlling muscle spasticity.
Nicholas LaRocca, vice president of health care delivery and policy research at the National Multiple Sclerosis Society, said the study was well done.
"For people with MS, spasticity is a major problem," he said. "Although treatments are available, they don't work for everyone with MS."
While the study showed good short-term effects of the cannabis, LaRocca said, "the study does show that smoking marijuana is not a long-term solution, because of the cognitive effects."
People with multiple sclerosis are already likely to have cognitive defects, he noted.
"We need to continue to search for not only other medicines for plasticity, but nonpharmacologic treatments," LaRocca said.
The study was funded by the University of California's Center for Medicinal Cannabis Research.
A typical marijuana cigarette has 0.5 grams of marijuana, according to ProCon.org, a nonprofit that discusses controversial issues such as medical marijuana. Average patient cost is about $8.57 per joint, it said.
To relieve spasticity, people with multiple sclerosis can also ask a physical therapist to show them exercises, according to the National Multiple Sclerosis Society. Another option is to get braces or splints prescribed to keep the leg in a more normal position and improve spasticity.
Copyright © 2012 HealthDay. All rights reserved.
SOURCES: Jody Corey-Bloom, M.D., Ph.D., professor, neurosciences, University of California, San Diego, and director, UCSD Multiple Sclerosis Center; Nicholas LaRocca, Ph.D., vice president, health care delivery and policy research, National Multiple Sclerosis Society, New York City; May 14, 2012, CMAJ (Canadian Medical Association Journal)