Multiple sclerosis (MS) is an autoimmune disease affecting the central nervous system (CNS), which includes the brain, spinal cord, and optic nerves. The nerves in the CNS are protected by a fatty material called the myelin, which helps nerve fibers conduct electrical impulses. In MS, when the immune system attacks the CNS, the myelin is damaged, resulting in the formation of scar tissue called sclerosis or plaques. This damage leads to a disruption in signaling along the nerves that travel to and from the brain and spinal cord, and produces a variety of symptoms that can range from mild numbness in the limbs to severe paralysis or loss of vision.

Who Gets MS?

It’s estimated that 400,000 people in the United States and 2.5 million people worldwide are living with MS, and more than 200 people are diagnosed with MS each week. MS symptoms typically begin between the ages of 20 and 40 years, and rarely occur prior to age10 or after age 60. MS is significantly more common (at least two to three times) in women than men, and the disease generally occurs five years earlier for women than for men.

What Causes MS?

The underlying cause of MS is unknown, but most researchers believe that the body’s immune system responds abnormally and attacks the CNS, damaging the myelin. Normally, the immune system defends the body against foreign invaders such as viruses or bacteria. In autoimmune diseases, the immune system attacks the body. In MS, the myelin is the target of the body’s attack. The disease is thought to result from a combination of factors, including genetics, an immune system malfunction, and environmental triggers such as viruses, trauma, vitamin deficiency, or exposure to heavy metals.