Multiple sclerosis has been recognized as a disease since the mid 1800s, but in some ways it's still a mystery. Scientists are working with several theories about the cause of multiple sclerosis.
Immune Response
MS is an autoimmune disease. In an autoimmune disease, the body mistakes some part of itself as a foreign invader. With MS, the part of the body that is mistaken as an invader is the protective covering of nerve fibers, the myelin sheath.
It's possible that the initial cause of MS could be an overreaction to a real foreign invader, such as a virus or bacteria. This overreaction could cause the immune system to attack myelin—in addition to the invading virus or bacteria—even after the foreign invader is gone.
Heredity Factors in MS
Our genes may have a key role in MS. People from different ethnic groups have different tendencies to develop MS: people of European descent are twice as likely to have MS as African Americans and Asian Americans.
MS also occurs more often in relatives of people with MS:
- Children, siblings, and non-identical twins of someone with MS have a one in 100 to one in 40 chance of having MS themselves.
- The identical twin of someone with MS has a one in four chance of having MS.
Geography
The place where you grew up also may play a role in determining how likely you are to get multiple sclerosis. Multiple sclerosis is more common in cooler areas of the globe.
- In the United States, Northern states have higher rates of MS than Southern states, and Canada has a rate of MS double that of the US.
Learn about the types of MS
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