Migraines affect about 1 billion people worldwide, and the onset of symptoms can be debilitating – from throbbing pain to nausea and sensitivity to light and sound. Now, a study involving more than 50,000 Danish patients has highlighted a link between migraines and potential heart health problems.

The study, published in The BMJ, analyzed patient records from 51,032 people treated for migraines at Danish hospitals and outpatient clinics between 1995 and 2013. The data were compared to 510,320 non-migraine patients. The researchers followed-up with the participants for 19 years.

The average age of the study participants at diagnosis of migraine was 35, and about 70 percent of the study population were women (migraines are known to disproportionately affect women).

The results showed that over the course of the study period, patients with migraines had a 49 percent increased chance of heart attack, and about double the risk of stroke compared to the non-migraine group. Additionally, migraine sufferers had a 59 percent increased risk of developing blood clots in their veins.

The risks were even higher within the first year of receiving a migraine diagnosis, but were shown to persist for up to two decades, according to the researchers. The statistics remained consistent after accounting for other risk factors such as excess weight and smoking.

The team also found that the association between migraines and heart problems was stronger in people who experienced visual disturbances known as “aura.”

Aura is one of the four stages of migraines. Not everyone experiences all the stages, but 25 percent of migraine sufferers experience aura, according to the Migraine Research Foundation. Aura symptoms usually occur before the migraine attack, and can include flashes of light, blind spots and other vision disturbances.

Migraine attacks can last anywhere between four and 72 hours. Migraine is the third most prevalent illness in the world, according to the Migraine Research Foundation.

The study did note that the absolute risk of a cardiovascular issue for individuals of the study was low, but that was not surprising given the average age of the participants was 35.

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

Researchers have a few theories on the association between migraines and increased risk of cardiovascular events. A sudden constriction of blood vessels in the brain is believed to lead to migraines, and this may also make the patient more susceptible to a stroke. Those who suffer from migraines also tend to remain stationary or lay down during attacks, which could contribute to an increased risk of blood clots.

“In this nationwide cohort study, migraine was associated with an increased risk of cardiovascular disease. This suggests that migraine should be considered a potent and persistent risk factor for most cardiovascular diseases in both men and women,” concluded the study authors. "The mechanisms by which migraine might increase cardiovascular disease risk are probably multifactorial."