Risk factors

These factors may increase your risk of developing multiple sclerosis:

• Age. MS can occur at any age, but onset usually occurs around 20 and 40 years of age. However, younger and older people can be affected.
• Sex. Women are more than two to three times as likely as men are to have relapsing-remitting MS.
• Family history. If one of your parents or siblings has had MS, you are at higher risk of developing the disease.
• Certain infections. A variety of viruses have been linked to MS, including Epstein-Barr, the virus that causes infectious mononucleosis.
• Race. White people, particularly those of Northern European descent, are at highest risk of developing MS. People of Asian, African or Native American descent have the lowest risk.
• Climate. MS is far more common in countries with temperate climates, including Canada, the northern United States, New Zealand, southeastern Australia and Europe.
• Vitamin D. Having low levels of vitamin D and low exposure to sunlight is associated with a greater risk of MS.
• Certain autoimmune diseases. You have a slightly higher risk of developing MS if you have other autoimmune disorders such as thyroid disease, pernicious anemia, psoriasis, type 1 diabetes or inflammatory bowel disease.
• Smoking. Smokers who experience an initial event of symptoms that may signal MS are more likely than nonsmokers to develop a second event that confirms relapsing-remitting MS.