Multiple sclerosis (or MS) is a chronic, often disabling disease that attacks the central nervous system (CNS), which is made up of the brain, spinal cord, and optic nerves. Symptoms may be mild, such as numbness in the limbs, or severe, such as paralysis or loss of vision. The progress, severity, and specific symptoms of MS are unpredictable and vary from one person to another. Today, new treatments and advances in research are giving new hope to people affected by the disease.

The body’Äôs own defense system attacks myelin, the fatty substance that surrounds and protects the nerve fibers in the central nervous system. The nerve fibers themselves can also be damaged. The damaged myelin forms scar tissue (sclerosis), which gives the disease its name. When any part of the myelin sheath or nerve fiber is damaged or destroyed, nerve impulses traveling to and from the brain and spinal cord are distorted or interrupted, producing the variety of symptoms that can occur.

Most people with MS learn to cope with the disease and continue to lead satisfying, productive lives.

While the cause (etiology) of MS is still not known, scientists believe that a combination of several factors may be involved. Studies are ongoing in the areas of immunology (the science of the body’Äôs immune system), epidemiology (that looks at patterns of disease in the population), and genetics in an effort to answer this important question. Understanding what causes MS will be an important step toward finding more effective ways to treat it and’Äîultimately’Äîcure it, or even prevent it from occurring in the first place.

In the United States today, there are approximately 400,000 people with multiple sclerosis (MS)’Äîwith 200 more people diagnosed every week. Worldwide, MS is thought to affect more than 2.5 million people. While the disease is not contagious or directly inherited, epidemiologists’Äîthe scientists who study patterns of disease’Äîhave identified factors in the distribution of MS around the world that may eventually help determine what causes the disease. These factors include gender, genetics, age, geography, and ethnic background.