Low Sunlight With Virus Linked To MS
As reported by ScienceDaily (4/11) Common Virus Plus Low Sunlight Exposure May Increase Risk of Multiple Sclerosis
New research suggests that people who are exposed to low levels of sunlight
coupled with a history of having a common virus known as mononucleosis may be
at greater odds of developing multiple sclerosis (MS) than those without the
virus. The research was published in the April 19, 2011 print issue of
Neurology®, the medical journal of the American Academy of Neurology.
"MS is more common at higher latitudes, farther away from the equator," said
George C. Ebers, MD, with the University of Oxford in the United Kingdom and a
member of the American Academy of Neurology. "Since the disease has been linked
to environmental factors such as low levels of sun exposure and a history of
infectious mononucleosis, we wanted to see whether the two together would help
explain the variance in the disease across the United Kingdom."
Infectious mononucleosis is a disease caused by the Epstein-Barr virus, which is
a Herpes virus that is extremely common but causes no symptoms in most people.
However, when a person contracts the virus as a teenager or adult, it often
leads to infectious mononucleosis. The body makes vitamin D when exposed to
ultraviolet B (UVB) light.
For the study, researchers looked at all hospital admissions to National Health
Service hospitals in England over seven years. Specifically, they identified
56,681 cases of multiple sclerosis and 14,621 cases of infectious
mononucleosis. Scientists also looked at NASA data on ultraviolet intensity in
England. The study found that adding the effects of sunlight exposure and
mononucleosis together explained 72 percent of the variance in the occurrence
of MS across the United Kingdom. Sunlight exposure alone accounted for 61
percent of the variance. "It's possible that vitamin D deficiency may lead to
an abnormal response to the Epstein-Barr virus," Ebers said.
He noted that low sunlight exposure in the spring was most strongly associated
with MS risk. "Lower levels of UVB in the spring season correspond with peak
risk of MS by birth month. More research should be done on whether increasing
UVB exposure or using vitamin D supplements and possible treatments or vaccines
for the Epstein-Barr virus could lead to fewer cases of MS." The study was
supported by the Multiple Sclerosis Society of Great Britain and Northern
Ireland, the Medical Research Council and the Wellcome Trust.