Women aged 45 and older who had the "aura" type of migraine also had a higher overall risk of cardiovascular disease (which includes heart disease and stroke).
It is not clear if these risks extended to younger women or to men, because they were not included in the study.
The findings can be considered good news for most women who suffer from migraines, the researchers conclude.
"Since migraine without aura is far more common than migraine with aura, our data demonstrate no increased risk of cardiovascular disease for the majority of migraine patients," wrote Tobias Kurth, M.D., and colleagues from Harvard Medical School's Brigham and Women's Hospital in Boston.
Migraines are more common in women than men. Three times as many women complained of having them in one study (18% versus 6%).
But typically only about a third to a fifth of migraine sufferers of either sex have aura symptoms.
An aura occurs before the onset of a migraine. Aura symptoms can include, but are not limited to, light flashes, blind spots, blurred vision, and the formation of dazzling zigzag lines during the migraine. Aura can also include changes in sensation and smell.
Twice The Risk
Several earlier studies have suggested a link between migraine with aura and stroke, but it has not been clear if this risk extended to other cardiovascular risks.
In an effort to help answer that question, researchers examined data from the ongoing Women's Health Study. Roughly 28,000 study participants were included in their investigation, published in the July 19 issue of the Journal of the American Medical Association.
All of the women were aged 45 or older when they joined the study between 1992 and 1995, and none had a history of cardiovascular disease or angina (chest pain due to heart disease).
Of the 3,610 women who reported having had a migraine headache over the previous year, 1,434 (39 percent) said their migraines included aura symptoms.
Women still having migraines with aura at study entry were roughly twice as likely as women with no migraine history to be diagnosed with a major cardiovascular event, such as heart attack, stroke, or angina over the next decade.
And these women were slightly more than twice as likely to die of cardiovascular disease.
But women having active migraine headaches without aura had the same heart and stroke risk as women with no migraine history.
Does Headache Treatment Lower Heart Risk?
In an editorial accompanying the study, longtime migraine researcher Richard B. Lipton, MD, suggested that genetic predisposition may explain the link between migraine with aura and cardiovascular disease.
Lipton tells WebMD that overexpression of a gene associated with increased blood levels of the amino acid homocysteine is common in people with migraine with aura. An elevated homocysteine level has been linked to increased risk of heart disease and stroke.
"If migraine with aura proves to be a risk factor for cardiovascular events in women, it will be no different from other risk factors like high blood pressure, diabetes, and cigarette smoking," says Lipton.
"What we don't yet know is whether good treatments for migraine with aura can decrease this risk in the same way that treating high blood pressure or stopping smoking can."
Studies designed to answer this question are needed, he says, as are those which seek to determine if the risk extends to younger women and to men.
In the meantime, physicians taking care of migraine with aura sufferers who have other risk factors for cardiovascular disease should be especially vigilant about managing these risk factors, he says.
Sources: Kurth, T. Journal of the American Medical Association, July 19, 2006; Vol. 296: pp. 283-291. Tobias Kurth, M.D., ScD, Division of Preventive Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston. Richard B. Lipton, departments of epidemiology and population health, Albert Einstein College of Medicine, Bronx, N.Y. Lipton et al., "Prevalence and Burden of Migraine in the U.S.," Headache, 2001; Vol. 41: pp. 646-657.
By Salynn Boyles
Reviewed by Louise Chang, M.D.
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