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November 2, 2006

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Tobias Kurth explains with equations and hand motions that migraines accompanied by visions of a pulsating aura signal a high risk for strokes, heart attacks, and deaths from cardiovascular disease. (Staff photo Jon Chase/Harvard News Office)

Migraine auras and heart disease linked - risks high for women

By William J. Cromie
Harvard News Office

Marsha T. saw the lights of pain coming. They flashed and zigzagged before her eyes. Her visual field shrank into a tunnel. A registered nurse, she knew what was next. In about 30 minutes, a familiar sharp, pulsating pain ripped through her head. Now 48 years old, she had been suffering from migraine headaches with aura since she was a teenager.

When the intense pain subsided, she relished the relief, but knew that the headaches would be back. Some 28 million people in the United States, most of them women, suffer from such repetitive, life-spoiling pain. And if that's not bad enough, evidence is accumulating that migraines are linked to an increased risk of major cardiovascular diseases, including stroke and heart attack.

A new study by researchers at Harvard Medical School and Harvard School of Public Health has found that women who experience migraine with aura have double the risk of major cardiovascular events compared with women who are free from these headaches. The researchers followed 27,840 nurses and other female health professionals, 45 years and older, for an average of 10 years. Those who endured migraine were more than twice as likely to have heart attacks and strokes as those who did not. And they were more than twice as likely to die of cardiovascular disease.

No one knows why. To add to the mystery, it was only women who live with migraine plus aura who were found to be at increased risk. "Active migraine without aura was not associated with increased risk of any cardiovascular event, including coronary revascularization and angina," reports Tobias Kurth, an assistant professor of medicine who works at Harvard-affiliated Brigham and Women's Hospital in Boston. Revascularization includes bypass surgery and techniques to open up arteries in the heart; angina involves a strangling heaviness or pain in the chest due to partially blocked coronary arteries.

Heart to head links

Kurth and his colleagues were aware that other researchers had found an increased frequency of strokes among young women with migraine, especially migraine with aura. These are strokes brought on by clots in arteries of the brain. Researchers usually work with females when studying migraines because women with these headaches outnumber men by about three to one.

There was clearly a need to take a more thorough look at what was going on between women's hearts and heads. Kurth and his team took advantage of the Women's Health Study, an ongoing national look at 39,876 female health professionals aged 45 years and older who were free of cardiovascular disease, cancer, and other major illnesses when they enrolled between 1992 and 1995.

During an average of 10 years follow-up, 3,610 women reported migraines within the past year, 1,434 of them with aura. The outcome was clear. The splitting headaches and pulsating lights not only match an increased risk of stroke but also signal a strikingly higher risk of other major cardiovascular diseases. And they raise the risk of death from major cardiovascular disease 2.3-fold compared with those without migraine with aura.

"Why?" Kurth was asked. "The short answer is, we don't know," he answered. However, he mentioned an association between migraine with aura and all the usual suspects involved in heart attacks and strokes - elevated cholesterol levels, high blood pressure, and other things that lead to dangerous narrowing of arteries. "Thus," says Kurth, "it's possible that migraine with aura may be a characteristic that identifies people at increased risk of progressive atherosclerosis," a thickening of the inner layer of artery walls that impairs blood flow.

Kurth and his colleagues also cast suspicion on genetic differences that are linked with a substance called homocysteine, high levels of which may increase risks for heart disease. "But at this point, everything is speculation," he admits.

The big question

Previous studies that found a link between migraine and stroke produced an unwanted consequence. That information led some migraine sufferers to fear that their auras and pain would bring on a stroke. "Now, as a result of our study, people may be afraid that migraine with aura will cause a heart attack," Kurth notes. "But they shouldn't worry, the two don't come together. Migraine with aura characterizes cardiovascular disease but it does not immediately cause it."

Acute migraines can be eased with a number of painkillers, including aspirin, acetaminophen, and ibuprofen. And many of them disappear with age. The big unknown is whether successfully treating migraine with aura will reduce the risk of heart attack, stroke, and other heart diseases. It will take a lot more research to answer that question.

In the meantime, Kurth advises those who suffer from the head pains and lights to build up their defenses against heart disease and stroke the same way that everyone else can, by not smoking; keeping blood pressure, cholesterol levels, and weight down; eating plenty of fruit, vegetables, and grains; and exercising.


Copyright 2006 by the President and Fellows of Harvard College