MS May Be Tied to Sunlight

Mononucleosis and low sunlight exposure may increase risk for multiple sclerosis

(RxWiki News) Experts are not sure what causes multiple sclerosis (MS). It could be caused by a virus, genetics, or the environment around patients. Now researchers are pointing out two new things that may increase a person's risk of MS.

Researchers found that people may have a higher risk of MS if they do not get a lot of sunlight and have a history of a virus called mononucleosis, more commonly known as "mono." The combination of low sunlight and mononucleosis helped the researchers explain the different rates of MS across parts of the United Kingdom.

"A common virus and low amounts of sunlight may increase your risk of MS."

According to Geroge C. Ebers, M.D., from the University of Oxford, MS is more common in areas further away from the equator. Because the disease had already been linked to low levels of sunlight and mononucleosis on their own, Ebers and colleagues wanted to see if the two together could account for the different rates of MS across the United Kingdom.

The body makes more vitamin D when it is exposed to sunlight. Ebers explains that not getting enough vitamin D may make people respond abnormally to the Epstein-Barr virus - a virus that can lead to mononucleosis and has been linked to MS.

Ebers concludes that more research should be done to see if doctors can reduce the risk of MS by increasing sunlight exposure or using vitamin D supplements in addition to treating Epstein-Barr virus.

In Depth

For their study, Ebers and colleagues looked at records of people admitted to English hospitals for multiple sclerosis or mononucleosis. Looking at data over a seven-year period, the researchers found 56,681 cases of multiple sclerosis and 14,621 cases of mononucleosis. They also looked at NASA data on the intensity of ultraviolet rays from the sun.

The researchers found:

  • Exposure to sunlight plus mononucleosis explained 72 percent of the variation in rates of MS across the United Kingdom
  • Sunlight exposure on its own explained 61 percent of the variation.
  • Risk of MS was most strongly linked to low levels of sunlight exposure in the spring  
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Review Date: 
April 22, 2011