"People with multiple sclerosis have long said that smoking marijuana helps ease their painful muscle cramping. And a new clinical trial suggests they are not just blowing smoke.  The study published Monday found that for  MS patients with muscle spasticity a few days of marijuana smoking brought some relief.  But the big caveat researchers say is that its not clear that the downsides of pot smoking are worth it.  Some people with MS are already using medical marijuana to treat certain symptoms including spasticity  when the muscles in the legs or arms contract painfully in something akin to a charley horse.  There is some science behind the idea The body naturally produces cannabinoids the group of chemicals found in marijuana. And studies have suggested the cannabinoid receptors on our cells help regulate muscle spasticity.  But the evidence that pot smoking actually helps with spasticity has been anecdotal.  Weve heard from patients that marijuana helps their spasticity but I think a lot us thought Well its probably just making you feel good said Dr. Jody CoreyBloom the lead researcher on the new study.  I think this study shows that yes marijuana may help with spasticity but at a cost said CoreyBloom of the University of California San Diego.  The cost her team found is that smoking caused fatigue and dizziness in some users and generally slowed down peoples mental skills soon after they used marijuana.  But its not clear if that would have any longterm consequences CoreyBloom said.  About  people in the United States have MS a chronic disease in which the protective coating around nerve fibers starts breaking down.  The new study reported in the Canadian Medical Association Journal included  MS patients with muscle spasticity that had failed to get better with standard medication.  CoreyBlooms team had each patient smoke marijuana or placebo joints  which looked smelled and tasted like the real thing but lacked the active ingredient in marijuana known as THC.  Each patient smoked marijuana once a day for three days and used the placebo cigarette once a day on three separate days. Before and after each treatment an independent rater assessed the patients muscle spasticity.  Overall the study found measures of spasticity dropped an average of three points about  percent  on a point scale when patients smoked marijuana but didnt change after they smoked the placebo.  The issue of treating spasticity is certainly an important one said Nicholas LaRocca vice president of healthcare delivery and policy research at the National MS Society.  Spasticity is a big problem for many people with MS and the current medications dont necessarily work for everyone said LaRocca who was not involved in the new study.  But smoking marijuana does not appear to be a longterm solution because of the cognitive effects he told Reuters Health.  People with MS are already at some risk of cognitive changes LaRocca pointed out so the potential for lasting effects from longterm marijuana smoking is a concern.  However LaRocca said researchers are developing cannabinoidbased medications for MS. That includes a cannabinoid mouth spray called Sativex that has been approved in the UK Canada Spain and New Zealand to treat MSrelated spasticity.  Research into cannabinoids and spasticity should continue LaRocca said because medications may be able to harness the benefits of specific cannabis compounds without the side effects linked to smoking pot.  Both LaRocca and CoreyBloom said there were limitations to the current study.  Blinding people as to whether they are on marijuana or a placebo is tough since the drug creates a high feeling.  In this study  of  patients were able to correctly guess whether they were using marijuana or a placebo at each of their six visits with the researchers. And the rest often guessed correctly.  Its pretty clear that the patients were not really blinded LaRocca said. What effects that might have had on the results is unclear.  CoreyBloom said that should not have influenced the spasticity findings since an independent researcher who didnt know whether patients were smoking marijuana or the placebo rated spasticity using a standard scale.  But another limitation she pointed out is that the study looked at the effects and side effects of marijuana over only a few days. We cant say anything about longterm effects CoreyBloom told Reuters Health.  For now LaRocca recommended that people with spasticity see a doctor experienced in treating MS. And if youre on an antispasticity medication and its not working well enough or the side effects are too much tell your doctor he said.  For some people a change in the medication dose might help.  SOURCE bit.lyqBMku httpbit.lyqBMku Canadian Medical Association Journal online May  . Our StandardsThe Thomson Reuters Trust Principles. httpthomsonreuters.comenaboutustrustprinciples.html"