Researchers Actively Exploring Causes of Multiple Sclerosis

Multiple sclerosis (MS) is one of the more common autoimmune diseases, affecting the central nervous system in the brain and the spinal cord. MS begins when the body's own immune system attacks myelin, the tissue that insulates nerves.

Symptoms of MS and their severity can vary widely among patients and range from vision loss or change, unusual fatigue, numbness or weakness, dizziness, "pins and needles" sensations, pain, speech impediments, cognitive deficits, tremors and even paralysis.

Medical College of Wisconsin Assistant Professor of Neurology Lea H. Rayman, MD, specializes in the diagnosis and treatment of multiple sclerosis and similar diseases. "We still don't completely understand why MS occurs or what triggers it," she says, "but we're learning more all the time."

Genetics, Hormones and Vitamin D
"There seems to be an underlying genetic predisposition, and that's one important area of study," she says. "Researchers are trying to unravel the genetic code for answers, and they've identified some of the genes that seem to influence MS. In fact, right now, it seems likely that several hundred genes may be involved." At least one of those genes seems to be associated with other autoimmune diseases, including type 1 diabetes and Graves' disease, which causes the thyroid gland to be overactive, she says.

There is also an environmental component, in that something patients are exposed to before puberty - probably a virus - sets up a condition in which they develop MS later in life.

"A hormonal component seems to influence the disease as well. We've observed that women with MS often discover their symptoms decrease during pregnancy, but there is a greater risk of relapse after they deliver."

She noted that one interesting new area of MS research involves a deficiency of vitamin D, sometimes referred to as the "sunshine vitamin." Adequate vitamin D levels appear to be protective against developing MS. Vitamin D deficiency is known to play a role in the development of osteoporosis (reduced bone mass), and some female MS patients are also at risk for developing osteoporosis.

Vitamin D deficiency is more common among people living in northern climates; it has also been implicated in hypertension, cancer, infections and other autoimmune disorders. A study published in January 2008 noted that vitamin D deficiency also seems to be involved in heart disease.

Dr. Rayman has been testing her MS patients' vitamin D levels, "and almost everyone was deficient in vitamin D."

Vaccine and New Drugs
While researchers try to discover what causes MS and other autoimmune diseases, "there are many new medications and treatments now available and on the horizon," Dr. Rayman says.

She notes that an experimental MS vaccine seems to help prevent myelin destruction in people with MS.

Years ago, MS patients weren't generally treated until their symptoms became severe, but newer approaches call for treating the disease early to improve outcomes. Newer drugs called immunomodulators can decrease the inflammatory process in the most common form of MS.

Dr. Rayman says patients treated at the Froedtert & Medical College Neuroscience Center may be prescribed one of four injectable drugs - Avonex, Betaseron, Rebif or Copaxone. All appear to reduce the central nervous system inflammation that creates many MS symptoms, and have been approved by the US Food and Drug Administration.

According to the National Institute of Neurological Disorders and Stroke, these drugs can reduce the number of MS episodes and could slow the progression of physical disability and decrease destruction of the myelin.

In addition, the newest MS drug, Tysabri (also called natalizumab), is a class of drug called monoclonal antibody. "It's highly effective in reducing disabilities, relapses and new lesions," Dr. Rayman says. Tysabri was withdrawn from the market by the FDA in February 2005, only three months after it was approved, when three patients out of 3,000 in a clinical trial developed a rare brain disease after taking it.

In March 2006, however, an FDA panel voted to reinstate the drug to carefully screened patients who are entered in a registry. "Currently, 36,000 patients around the world have taken Tysabri and 3,600 of them have taken it for 18 months or more," Dr. Rayman says, including some of her patients.

"Another promising drug on the horizon is fingolimod, which is administered orally," she notes. It's still undergoing investigation and is not yet available at the Neuroscience Center.

"Thanks to technological advances, I've seen our understanding of MS change hugely just since 1990, when I completed my medical residency," Dr. Rayman says. "And it keeps getting better."

Along with her colleague Douglas Woo, MD, Dr. Rayman sees patients at the Froedtert & Medical College Neuroscience Center.

Barbara Abel
HealthLink Contributing Writer

For more information on this topic, see the HealthLink article Autoimmune Disorders: When the Body Attacks.

MCW Health News presents up-to-date information on patient care and medical research by the physicians of the Medical College of Wisconsin.