People who suffer migraines may have a higher risk of heart attack or stroke than those without the painful headaches, research published Wednesday suggests.In a study of more than 11,000 U.S. adults with and without migraines, researchers found that migraine sufferers were more likely to say they had ever had a heart attack, stroke or symptoms of peripheral artery disease — narrowing in the blood vessels supplying the legs.

The findings, reported in the journal Neurology, add to evidence linking migraines to an increased risk of cardiovascular disease.

They also suggest that the risks are not limited to people whose migraines are accompanied by neurological symptoms known as "aura" — visual disturbances, numbness, tingling or other bodily sensations that precede the headache.

Previous studies have uncovered higher risks of heart problems and stroke among adults with migraine plus aura, but findings have been less consistent regarding people who have migraines without aura — the group that accounts for about 80 percent of migraine sufferers.

Still, these latest findings should not scare people battling migraines, an expert not involved in the study told Reuters Health.As a group, migraine sufferers might have a relatively higher risk of cardiovascular problems, but their absolute risk is small, noted Dr. Hans-Christoph Diener, a researcher at the University Hospital Essen, in Germany, who wrote an editorial published with the study.

For example, of the 6,100 migraine patients in the study, 4 percent reported a history of heart attack. The rate was 2 percent among the 5,243 people in the comparison group without migraine.

Similarly, 2 percent of the migraine group reported a history of stroke, versus 1.2 percent of the comparison group. A further look showed that the increased stroke risk was only in the migraine with aura group; nearly 4 percent had a history of stroke, compared with just over 1 percent of migraine sufferers without aura symptoms.

The researchers on the study, led by Dr. Marcelo E. Bigal of Merck Research Laboratories, agree that the absolute risks are small.

They add, though, that the findings should encourage migraine sufferers to be particularly careful about curbing the more common and significant risk factors for heart disease and stroke — such as high blood pressure, high cholesterol and obesity.

The researchers found that the people with migraine did have higher rates of high blood pressure, high cholesterol and diabetes than those in the comparison group. Those rates did not, however, explain the link between migraine and heart problems and stroke.

So exactly why migraine is connected to cardiovascular disease remains unclear. One possibility, Diener said, is that some people have an underlying susceptibility to both migraines and cardiovascular disease.

The precise cause of migraine headache is not fully understood, but the pain involves constriction, and then swelling, of brain blood vessels. The current findings, according to Diener, support the notion that people with migraine may have dysfunction in the blood vessels throughout the body.

According to Bigal's team, future studies should look at whether certain migraine sufferers are at particular risk of heart problems and stroke — such as those with frequent headaches or frequent aura symptoms.

They say research should also investigate the effects of migraine treatment.

On one hand, the researchers note, drugs that prevent migraine attacks could theoretically lower the risk of cardiovascular problems. On the other, certain medications might have negative effects; some anti-inflammatory painkillers have been linked to cardiovascular risks, the researchers point out, while migraine drugs known as "ergots" tend to constrict blood vessels throughout the body.

Merck & Co. Inc., which makes the migraine drug Maxalt (rizatriptan), funded the study. Bigal and other researchers on the work are employees of Merck or have financial ties to it or other drug companies. Diener, the author of the editorial, has received funds from various drug companies.