Aug. 24, 2010 -- Evidence is accumulating that migraines with aura -- a transient visual or sensory disturbance, such as light flashes or zigzag patterns-- may increase the risk of heart disease and stroke.
Researchers have also found that migraine with aura seems to boost the risk of earlier death from any cause, including cardiovascular disease, compared to those who don’t have the condition, and that women with migraine with aura may be at increased risk for an additional type of stroke called hemorrhagic stroke.
The two new studies, both published in BMJ, add to the evidence of a suspected migraine-disease link. But both research teams say the findings should not alarm those who suffer migraine with aura because the risk is still low.
''We don't want to scare people at all," researcher Tobias Kurth, MD, ScD, director of research at INSERM at the Hospital del la Pitie Salpetriere in Paris, tells WebMD. The vast majority of migraine sufferers, he says, will not get a stroke because of their migraines.
More than 29 million Americans suffer from migraines, according to the National Headache Foundation. About 20% of middle-age women have migraines, the researchers say, and up to a third have the aura.
Migraines and Stroke Risk: The New Studies
In one study, researchers looked at nearly 19,000 men and women born between 1907 and 1935 who were enrolled in the Reykjavik (Iceland) Study, set up to study heart disease.
The researchers followed the men and women for 26 years, looking at death from all causes, including heart disease. They had information on which men and women had migraines, with or without aura, and also non-migraine headaches.
They found those with migraine with aura were about 21% more likely to die during the follow-up than those without the condition, and 27% more likely to die from cardiovascular disease compared to those with no headache.
Women with migraine with aura were 19% more likely to die from non-cardiovascular disease than those without.
The absolute risk, however, is low, says researcher Larus Gudmundsson, a doctoral student at the University of Iceland, Reykjavik. "'In people with migraine with aura, compared to those without headache, the excess absolute 10-year risk of cardiovascular disease mortality (including heart disease and stroke) at age 50 was low: 1.1% for men and 0.1% for women.
"From that we can calculate that due to migraine with aura, 11 extra men per 10,000 persons per year will die from cardiovascular disease and one extra woman per 10,000 persons per year."
In Kurth's study, he looked at the nearly 28,000 women participating in the U.S.-based Women's Health Study, set up to look at the benefits and risks of low-dose aspirin and vitamin E in preventing cardiovascular disease and cancer among healthy women.
Kurth evaluated the information the women had provided about their history of migraine and followed them to see when hemorrhagic stroke might have occurred. Hemorrhagic strokes involve a ruptured blood vessel, while ischemic strokes, linked in other research with migraines, are due to a clot within the blood vessel.
In his 2005 study of the same study participants, Kurth tells WebMD, ''We looked at hemorrhagic stroke and didn't find a significant association [with migraine with aura]. Now, with longer follow-up, we see the significant association."
In his study, women with active migraine with aura -- but not migraine without aura -- had more than a twofold increased risk of hemorrhagic stroke compared with those with no migraine history. To put it in perspective, he says: 'We are talking four additional events for 10,000 women with migraine with aura per year."
What is it about the aura? It's not clear, Kurth says. ''There are probably several mechanisms, including genetic susceptibility, plus potential involvement of the arteries throughout the body plus involvement of other cardiovascular risk factors."
Gudmundsson reports getting a travel grant from the Pharmaceutical Society of Iceland Science Fund, while his co-authors report serving on boards for pharmaceutical companies and receiving travel grants from the American Headache Society. Kurth has received research funds from Merck and the Migraine Research Foundation and honoraria from other drug companies for educational lectures.
The new research ''confirms a suspicion that many of us have had for many years, that migraine with aura is a significant risk factor for stroke," says Patrick Lyden, MD, chair of the department of neurology and the Carmen and Louis Warschaw Chair in Neurology, Cedars-Sinai Medical Center, Los Angeles, who reviewed the research for WebMD.
The Kurth research, he says, suggests the stroke risk may extend to the hemorrhagic type.
He, too, puts the new research findings in perspective. "This does not mean if you have a migraine you should run into the ER for a heart attack workup or a stroke workup," Lyden tells WebMD.
It does mean those with migraine should be aware of the potential increased risk, he says. "If you have migraine, you need to talk to your doctor and control your [other] risk factors [for stroke]," Lyden says. That includes controlling high cholesterol and high blood pressure.
Lyden suggests asking your doctor to review your medications for migraine, to be sure they are the best for you.