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Marijuana and MS--an unfinished story.


There is a growing trend for states to legalize marijuana for medical use. In January 2010, New Jersey became the 14th state to approve it, and many other states have pending legislation or other ongoing efforts aimed at legalization. In states with medical marijuana laws, MS or an MS symptom such as muscle stiffness (spasticity) is almost always listed among the conditions for which there is legal protection. These laws have given rise to massive growth in state "medical marijuana industries." It seems to me that Denver now has more marijuana dispensaries than Starbucks stores.

In the meantime, debates have intensified about the roles that patients, health-care providers and the law should ultimately play in making decisions about medical therapies. Because MS is mentioned specifically in many state laws, it is sometimes believed that the benefits in MS are proven--and that limitations on access are due purely to legal matters.

But there are many unanswered questions about marijuana's potential risks and benefits. What have scientific and clinical studies shown about the safety and effectiveness of marijuana for people with MS?

The fascinating science of marijuana

In the 1990s, there were remarkable advances in our understanding of how the chemical compounds in marijuana act on the human body.

Initially, it was found that these compounds, which are known as "cannabinoids" and include THC (tetrahydrocannabinol), produce biochemical effects by attaching to specific proteins on the surface of cells. These proteins are known as receptors. One form of cannabinoid receptors is found in the brain and acts to decrease the activity of nerve cells that are firing excessively. Through this mechanism, marijuana could, in theory, play a role in alleviating some MS symptoms, such as spasticity and pain. Another type of cannabinoid receptor is present on immune cells and acts to mildly decrease immune system activity. Through these immune-cell receptors (as well as other mechanisms), marijuana could possibly slow down the disease process of MS.

The body has receptors for molecules that are expected to occur. Therefore, scientists realized the body must make its own marijuana-like chemicals that have roles in normal body functioning. After all, these receptors don't exist in the human body just in case a person uses marijuana in her or his lifetime. Indeed, it has since been established that the body makes several "endocannabinoids." These chemicals are the body's version of marijuana in much the same way that "endorphins" are the body's own version of opium and morphine.

Study limitations

Animal studies suggest that marijuana may have beneficial effects in MS. In EAE, the animal model of MS, marijuana compounds have been seen to relieve symptoms, including muscle stiffness and tremor, and to decrease the overall severity of the disease. Here is the caution, however. MS is a complex disease for which the scientific understanding is incomplete and the animal model is imperfect. Only humans get true MS. Even if a therapy produces suggestive results in laboratory and animal studies, it is absolutely essential to do large-scale clinical trials in people with MS.

There have been many studies of marijuana in people with MS. Many of them have indicated that marijuana alleviates muscle stiffness, pain, sleeping problems and bladder difficulties. But there have been significant limitations to most of these studies, ranging from very small numbers of people to poor study design. The first large, rigorous trial of marijuana in MS, known as the

"CAMS" study, was conducted several years ago in the United Kingdom and found that THC produced a small benefit on muscle stiffness and a possible benefit on disability. An oral spray form of marijuana ("Sativex"), which is available by prescription in Canada, has produced beneficial effects on MS symptoms in some, but not all, studies. More clinical research has been called for and a large, well-designed study of people with progressive forms of MS, the "CUPID" trial, is currently underway in the United Kingdom.

Medical risks vs. benefits

Marijuana use is associated with significant side effects. It may cause sedation, increased appetite, cognitive impairment, psychiatric problems and poor outcomes of pregnancy, including complications with labor, low birth weight and delayed cognitive development in children. It may increase seizure risk and impair driving ability. High doses may cause incoordination and visual difficulties, contribute to heart attacks, and result in dependence and apathy. Marijuana may also increase the sedating or activating effects of other medications. The long-term use of smoked marijuana may impair lung function and increase the risk of cancer of the head, neck and lung.

Benefits in MS to offset such significant risks are not yet proven scientifically. Legalization for medical use in MS does not mean that the benefits and risks of marijuana for MS are definitively understood by medical science.

Many factors in the balance

When considering any medical therapy, it is essential to be well informed. One needs objective information about all the possible therapies available for a specific condition. Conventional medical therapies exist for many MS symptoms. These may be well tolerated and effective for some people, and, for others, may produce intolerable side effects or be ineffective or only partially effective. Thoughtful decision-making means carefully weighing all risks and benefits. Patients and their doctors often make trial runs on therapies and dosages. People with MS should discuss their individual options with trusted health-care providers, as there are many factors in the balance.

A Google search on "medical marijuana and multiple sclerosis" yields whopping results. What have clinical studies really shown about its safety and effectiveness for people with MS?


As a provider of MS care in Colorado, a state in which medical marijuana has been legal for nearly 10 years, I have made several observations. The majority of my patients don't use marijuana and don't seem particularly interested in it. Those who do use it span a spectrum: On one end are people who used marijuana recreationally for years before their MS diagnosis and want to continue using it for recreation. Now, they also hope it may provide some therapeutic effects for their MS. On the other end are people, including elderly ones, who are embarrassed even to talk about the subject. They have no past history of marijuana use, but have found that marijuana relieves some of their symptoms more effectively or with fewer side effects than the conventional medications. Of the users among my patients, the symptom that seems to be most consistently relieved by marijuana is the muscle stiffness or spasticity that interferes with sleep ("nocturnal spasticity").

On the legal side, for patients and clinicians (including me), there is an ongoing concern that, even though it is legal in Colorado, medical marijuana remains illegal at the federal level. Prior to the easing of the prosecution policy in October 2009, the federal government stringently enforced federal laws prohibiting marijuana use irrespective of state medical marijuana laws.


Update on Society-funded spasticity research

The National MS Society is very concerned about the lack of more effective treatments to control spasticity (see page 44) and has funded a pilot study of cannabis at the University of California, Davis, Medical Center. The results are not yet public. In the meantime, the Society's drug-development arm, Fast Forward, LLC, entered partnership with Canbex Therapeutics, in London, to pursue the pivotal studies needed to support a new drug application to the FDA. These studies focus on a completely different approach: a small molecule compound called VS N16R, which has shown promising ability to relieve muscle stiffness and pain without unwanted side effects. Visit News on our home page for the May 26, 2010, announcement.

Allen C. Bowling MD, PhD

Dr. Allen Bowling is the Medical Director of the Multiple Sclerosis Service and Director of the Complementary and Alternative Medicine Service at the Colorado Neurological Institute. He is also Clinical Associate Professor of Neurology at the University of Colorado. Additional information about unconventional medicine may be found in his highly recommended book, Complementary and Alternative Medicine and Multiple Sclerosis (2nd edition, Demos Medical Publishing), and on his website,
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Author:Bowling, Allen C.
Date:Sep 17, 2010
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