WASHINGTON, Sept. 12 (UPI) -- Scientists said Monday that oral contraceptives can significantly reduce the risk of multiple sclerosis, a finding that may allow for a better understanding of what causes the debilitating disorder and other similar illnesses.
"The incidence of MS in (oral contraceptives) users was 40 percent lower than in nonusers," Dr. Alvaro Alonso of the Harvard School of Public Health and colleagues report in the September issue of the Archives of Neurology.
Nicholas Larocca, director of healthcare delivery and policy research at the National Multiple Sclerosis Society, which funded the study, said the research may help elucidate why women are more likely to develop MS and other autoimmune diseases.
"There's been evidence for some time that there's some relationship between sex hormones and immune- mediated conditions like MS," Larocca told United Press International. "This adds another bit of evidence to that idea."
Larocca also said he thinks this is an issue "that is important to look at and it could be very import in the long run in our understanding of MS."
In the study, Alonso and colleagues compared 106 women who were diagnosed with multiple sclerosis with 1,001 women without the disorder. Those taking oral contraceptives -- also known as "the pill" -- experienced a 40 percent lowered rate of MS.
The first symptoms of MS often occur between the ages of 20 and 40. The cause of the disease is unknown, but it appears to be due to the immune system malfunctioning and attacking myelin, the tissue that insulates nerves. The symptoms can be mild in some, but most MS sufferers will develop muscle weakness and difficulty with coordination and balance.
Alonso's team thinks the estrogen contained in oral contraceptives may account for the lowered risk of MS. Previous research has found that estrogen delayed onset of a multiple sclerosis-like disease in animals, and the present study found a higher risk of developing MS the six months after a pregnancy compared to women who were not pregnant. During pregnancy, women had about the same risk as non-pregnant women.
Larocca noted the study only ran for three years, so the long-term effects of oral contraceptives on MS and whether the medications actually prevent the disease are not yet known.
He said his own group has funded research looking at gender and the relationship to autoimmune diseases and they "are hoping in the future that we will have a lot more answers than we have now."
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