Feb. 16, 2010 -- Women with a history of migraines may be more likely to develop multiple sclerosis than women without the headaches, but it is not clear if migraines are a risk factor for the neurological disorder.
In the first large-scale study to examine the relationship between migraines and multiple sclerosis (MS), researchers found that migraine sufferers were roughly 50% more likely to develop MS as non-sufferers, although the overall risk for MS was very small.
More research is needed to understand if migraines have a causal role in the development of MS, neurologist and study researcher Ilya Kister, MD, of New York University Medical School tells WebMD.
"We can't say if migraines slightly increase a person's chances of developing MS, or if they are one of the early symptoms of MS," he says. "What we can say is that individual migraine patients have little cause for panic or concern because more than 99% of them will never develop MS."
Women are twice as likely to develop multiple sclerosis as men and three times as likely to suffer from migraines. And both conditions are most often diagnosed before the age of 50.
While several previous studies have shown migraines to be common among patients being treated for MS, it has not been clear if the association was real, Kister says.
"These studies were done in clinic populations and these populations tend to report more symptoms in general," he says.
In an effort to better understand the prevalence and impact of migraines in patients with MS, Kister and colleagues analyzed data from more than 116,600 female nurses participating in a nationwide health study.
The women were enrolled in the Nurses' Health Study II in 1989 and they were followed for 16 years.
Roughly 18,000 reported a physician-diagnosed history of migraines at enrollment and 375 were diagnosed with MS during the study.
After adjusting for other suspected risk factors for MS, having a history of migraines was associated with a 47% increase in risk for developing the disorder.
As yet unpublished data revealed that a diagnosis of MS was also associated with an increased risk for developing migraines, Kister says.
His study was made public today and will be presented at the annual meeting of the American Academy of Neurology in mid-April.
"Clearly, this is not a simple relationship," he says. "These two conditions seem to be linked somehow, but the relationship runs both ways."