Women who use the pill may find their risk of multiple sclerosis (MS) has eased, at least temporarily. Doctors at the Harvard School of Public Health released findings of a study this month that suggested those who take oral contraceptives cut their risk nearly in half.1
Alvaro Alonso, MD, PhD, and his colleagues at the Harvard School of Public Health in Boston also found that women who were pregnant faced the same lower risk.
"Recent OC [oral contraceptive] use, and possibly, current pregnancy, are associated with a lower risk of developing MS," Alonso explained. "On the contrary, the postpartum period confers a higher risk of MS onset."
Prevalence of MS
Multiple sclerosis is believed to be a disease that inherently lies in a person's immune system. The disease occurs, experts believe, because the immune system mistakenly lashes out against the body's own tissue; specifically, a fatty substance in the central nervous system known as myelin, which protects nerve fibers and allows them to conduct electrical impulses. In the immune attack, myelin and their underlying nerve fibers become damaged, leaving lesions where the damage occurs, disrupting communication between nerve fibers, and causing the symptoms commonly seen in the disease.2
It's estimated that approximately 400,000 Americans have MS, with women more likely to contract it than men, especially those between the ages of 20 and 50. Studies have suggested that there are certain people who are more genetically susceptible to the illness, but there is no evidence that MS is directly inherited. The disease also occurs more often in people of northern European ancestry.3
A Hormonal Link?
Previous research published in the medical literature had suggested that hormone treatments helped ease the effects of experimental autoimmune encephalomyelitis (EAE),4,5 a disease with the same features as MS, but used in animal studies. Thus, Alonso's group wanted to find out if hormone-based medications, such as oral contraceptives, or pregnancy, might have a similar effect on the development of multiple sclerosis.
To find out, the researchers reviewed the medical records of more than 3 million British residents maintained in a national database in the UK. Patients' identifying information had been removed. They found information on 106 women under age 50, who had been diagnosed with MS and had used oral contraceptives. Each of them had visited general practitioners between 1993 and 2000. For this study, those in the group with MS were compared with more than 1,000 females without the disease during the same time period.
Effect of Oral Contraceptives Seen
Using statistical analysis, the researchers discovered that the incidence of MS in the women taking oral contraceptives was 40% lower than in those not taking the medication. The risk was also lower in those who had been pregnant during the study period—though not significantly—and then nearly tripling in the 6-month postpartum period.
"This is consistent with studies on the effect of pregnancy in patients with MS, and the immunological changes associated with pregnancy," Alonso explained. "Our findings suggest that high levels of exogenous [given as medication] estrogens from oral contraceptive use and of endogenous [naturally-produced] estrogens during pregnancy may delay the first clinical attack of MS."
Potential Reasons
He explained that estrogen exerts a beneficial effect in this case on the immune system. Since MS is thought to be an autoimmune disease, there is a possible link between the two. "These observations could be explained by estrogen's ability to modulate the immune response and their potential neuroprotective effect," the researchers wrote.
While it appears that estrogens have some beneficial effect on the immune system, which would at least partly explain why disease reduction occurs during pregnancy, "it is not completely clear why oral contraceptives could reduce the risk of MS," Alonso said, in an interview.
Alonso predicted that those predisposed to developing MS could possibly delay its onset for up to two years by taking oral contraceptives.
However, he stressed that women shouldn't make decisions about taking oral contraceptives or become pregnant based solely on their possible influence on the development of multiple sclerosis. "We believe that our results indicate that decisions about use of oral contraceptives or pregnancies should not be based on fear of developing MS," Alonso told Priority Healthcare.
The study was published in September issue of the journal Archives of Neurology.
1. Alonso A, Jick SS, Olek MJ, Ascherio A, Jick H, Hernan MA. Recent use of oral contraceptives and the risk of multiple sclerosis. Arch Neurol 2005 Sep;62(9):1362-5.
2. National Multiple Sclerosis Society. What is Multiple Sclerosis? Available at: http://www.nationalmssociety.org/What%20is%20MS.asp. Accessed September 23, 2005.
3. National Multiple Sclerosis Society. Who Gets MS? Available at: http://www.nationalmssociety.org/Who%20gets%20MS.asp. Accessed September 23, 2005.
4. Jansson L, Olsson T, Holmdahl R. Estrogen induces a potent suppression of experimental autoimmune encephalomyelitis and collagen-induced arthritis in mice. J Neuroimmunol 1994 Sep;53(2):203-7.
5. Trooster WJ, Tellken AW, Kampinga J, Loof JG, Nieuwenhuis P, Minderhoud JM. Suppression of acute experimental allergic encephalomyelitis by the synthetic sex hormone 17-alpha-ethinylestradiol: an immunological study in the Lewis rat. Int Arch Allergy Immunol 1993;102(2):133-40.
John Martin is a long-time health journalist and an editor for Priority Healthcare. His credits include overseeing health news coverage for the website of Fox Television's The Health Network, and articles for the New York Post and other consumer and trade publications.
