A new study brings some concerning news for the millions who experience migraine attacks; scientists found that migraine may increase the risk of heart attack, stroke, and other forms of cardiovascular disease.

Based on these findings, the researchers—at Aarhus University Hospital in Denmark as well as Stanford University in California—say that migraine should be considered as a risk factor for cardiovascular disease.

Study co-author Henrik Toft Sørensen, from the Department of Clinical Epidemiology at Aarhus University Hospital, and colleagues recently reported their results in The BMJ.

As the Migraine Research Foundation point out, migraine is "not just a bad headache." Instead, it is a debilitating condition characterized by a recurring, severe pain on one or both sides of the head.

Migraine may also be accompanied by other symptoms, including dizziness, nausea, vomiting, sensitivity to light, and visual problems. When visual or other sensory problems occur, this is referred to as "migraine with aura."

It is estimated that migraine affects around 39 million people in the United States. Migraine attacks can last from anywhere between 4 and 72 hours, and more than 90% of those who experience migraine are unable to carry out their day-to-day activities as a result.

But according to Sørensen and team, migraine may pose more serious problems.

Cardiovascular risk heightened by migraine

Previous research has indicated that people with migraine—especially women—may be more likely to experience cardiovascular problems than those without migraine.

For the study, Sørensen and his team wanted to learn more about the link between migraine and cardiovascular disease, which is an umbrella term for conditions that affect the heart and blood vessels, such as stroke, heart attack, atrial fibrillation, and heart failure.

The scientists gathered data from the 1995–2013 Danish National Patient Registry, which included 51,032 people with migraine. For each person with migraine, the team matched 10 people without migraine who were the same age and sex. This gave them a total of 510,320 migraine-free subjects.

Compared with people who did not experience migraine, the study revealed that people with migraine were more likely to have a heart attack, stroke, or atrial fibrillation over 19 years of follow-up.

In detail, the researchers found that 25 in every 1,000 people with migraine had a heart attack, compared with 17 in every 1,000 migraine-free adults.

For every 1,000 people with migraine, 45 had an ischemic stroke—caused by a blood clot in the brain—compared with 25 in every 1,000 migraine-free subjects.

Atrial fibrillation occurred in 47 of every 1,000 people with migraine, compared with 34 in every 1,000 people without migraine.

Incidence of heart failure was similar in both groups, the researchers report, and no significant link was found between migraine and peripheral artery disease.

Women with migraine and people who had migraine with aura were found to have the greatest risks of stroke, heart attack, and atrial fibrillation, and the associations were strongest in the first year after migraine diagnosis.

These findings remained after accounting for a number of confounding factors, such as BMI and smoking status.

A 'potent and persistent risk factor'

Sørensen and team note that their study is purely observational, so they are unable to prove cause and effect between migraine and cardiovascular health.

Still, they believe that their findings—combined with those of other studies—indicate that migraine should be deemed a significant risk factor for cardiovascular disease.

"Although the magnitude of the increased cardiovascular risk associated with migraine was fairly small at the individual level," the authors explain, "it translates into a substantial increase in risk at the population level, because migraine is a common disease."

"This suggests that migraine should be considered a potent and persistent risk factor for most cardiovascular diseases in both men and women."

In an editorial linked to the study, Professor Tobias Kurth—of the Institute of Public Health at Charité–Universitätsmedizin Berlin in Germany—and colleagues say that there is now "plenty of evidence that migraine should be taken seriously as a strong cardiovascular risk marker."

"We urgently need," add the authors, "to determine which specific strategies reduce the additional risk of cardiovascular disease among people with migraine and whether reducing the frequency of attacks has any effect."

"Public research agencies must act quickly by investing in prospective studies to accomplish this goal."