Several factors may increase your risk of developing multiple sclerosis, including:

  • Age. Multiple sclerosis can occur at any age, but most commonly affects people who are ages 20 to 40.
  • Gender. Women are about twice as likely as men to develop multiple sclerosis.
  • Family history. If one of your parents or siblings has multiple sclerosis, you have a 1 to 3 percent chance of developing the disease — as compared with the risk in the general population, which is just a tenth of 1 percent.

    However, the experiences of identical twins show that heredity can't be the only factor involved. If multiple sclerosis was determined solely by genetics, identical twins would have identical risks. However, an identical twin has only about a 30 percent chance of developing multiple sclerosis if his or her twin already has the disease.

  • Certain infections. A variety of viruses, such as Epstein-Barr virus and others, appear to be associated with multiple sclerosis. Researchers study how some infections may be linked to the development of multiple sclerosis.
  • Ethnicity. White people, particularly those whose families originated in northern Europe, are at highest risk of developing multiple sclerosis. People of Asian, African or Native American descent have the lowest risk.
  • Geographic regions. Multiple sclerosis is far more common in areas such as Europe, southern Canada, northern United States, New Zealand and southeastern Australia. Researchers study why multiple sclerosis appears to more common in certain geographic regions.

    If a child moves from a high-risk area to a low-risk area, or vice versa, he or she tends to acquire the risk level associated with his or her new home area. But if the move occurs after puberty, the young adult usually retains the risk level associated with his or her first home.

  • Other autoimmune diseases. You may be slightly more likely to develop multiple sclerosis if you have thyroid disease, type 1 diabetes or inflammatory bowel disease.
Dec. 15, 2012