Female migraineurs have higher rates of multiple sclerosis than those who do not experience headaches.
Toronto—Women with migraines have a 48% higher risk of developing multiple sclerosis (MS) than those who do not have migraines, according to research presented at the 62nd Annual Meeting of the American Academy of Neurology. Using data from the Nurses Health Study II (NHS-2), investigators determined that the absolute risk of developing MS was 0.46% for women with migraines and 0.30% for those without, making it a “modest predictor of MS compared to the established risk factors.”
In a prospective cohort study, Ilya Kister, MD, of the MS Care Center, Department of Neurology, New York University School of Medicine in New York City, and colleagues examined the relationship between migraine and MS in the large population-based NHS-2 dataset, which included more than 116,000 female registered nurses from 14 states, who were ages 25 to 42 in 1989. At enrollment, 140 subjects had pre-existing MS (prevalent group), and an additional 375 women were diagnosed with MS after enrollment (incident group). Of the incident group, symptom onset was before 1989 in 92 women, after 1989 in 240 women (new onset), and unknown in 43 women.
Investigators used Cox proportional hazard regression to estimate rate ratios for being diagnosed with MS in women with and without pre-existing migraine, and adjusted for age, latitude of residence at age 15, ethnicity (Scandinavian, Southern European, other Caucasian, and other), smoking history in pack years, BMI at age 18, and supplemental vitamin D in 1991.
At baseline, 17,893 women (15.4%) reported a physician diagnosis of migraine. The researchers found that this group had a 47% greater risk of being diagnosed with MS in the next six years. An additional 6,407 women reported a diagnosis of migraine by 1995, for a cumulative migraine prevalence of 20.9%. For the cumulative total, investigators found a 1.48 increased risk of new onset MS than those who did not have migraine.
“Migraine is a very common disorder, reported by about 18% of women in the US, so it is not surprising that many women with MS report migraines as well,” Dr. Kister told Neurology Reviews. “There is likely an association between migraine in MS, but we are not sure what the causes are. It is possible that in some small minority of women, migraine headache is actually an early symptom of MS.”
Dr. Kister noted that migraine appears to be a lesser predictor of MS than is low vitamin D status, history of infectious mononucleosis, or positive DRB1*1501 haplotype. Investigators also observed a trend for MS patients to develop migraines at a higher rate than for non-MS patients, but it did not reach statistical significance.
“The literature on MS/migraine connection is conflicted—some studies show that migraine is more common among MS patients than in the general population, and others don’t show it is more common,” Dr. Kister noted. “While our study found women with migraine were more likely to develop MS later on, about a 50% relative risk, it is important to note the absolute risk of MS in women migraineurs was still very small. More than 99% of migraineurs will not develop MS.”
—Rebecca K. Abma
Suggested Reading
La Mantia L. Headache and multiple sclerosis: clinical and therapeutic correlations. Neurol Sci. 2009;30(Suppl 1):S23-S26.