Are There Environmental Factors That Can Cause MS?

Neurologist Lauren B. Krupp, M.D., director of NYU Langone’s Multiple Sclerosis Comprehensive Care Center in New York City, describes the complex equation of factors that come together to cause multiple sclerosis.

A good question is, what are some of the environmental factors that lead to the development of MS? There are actually a number of factors, and most of them, we think, have their influence early in someone's life, not at the time that they're necessarily experiencing symptoms.

Those factors include sun exposure, which is our biggest source of vitamin D. We think vitamin D is important in terms of MS. Less sun exposure increases your risk for MS. Certain viral exposures, which are unavoidable, seem to be, when they occur at a certain age, important in the development of MS in particular the virus EBV, which is what causes infectious mononucleosis.

Other environmental factors include exposure to smoke. We know that MS is more common in smokers compared to nonsmokers. Actually, where you live seems to be a factor, as well. People who live furthest from the equator have a higher frequency of MS than people who live close to the equator. We think that has to do with sun exposure and again, vitamin D, but there may be other aspects of sunlight like ultraviolet light that is important, too.