Migraines are bad enough on their own. Now it turns out that the debilitating headaches magnify stroke risks -- and that birth control pills increase the stroke potential even more.
Although the new finding suggests that migraines are a risk factor for stroke, researchers hasten to add that this should not be a cause for alarm. "The actual risk of stroke for migraine sufferers is still extremely low," says Mahyar Etminan, the study's lead author and an epidemiologist at Royal Victoria Hospital in Montreal. "The importance of this study is that if these two conditions are related and are caused by similar mechanisms, then it could help us come up with better migraine treatments."
Researchers in Canada and the United States pooled the data from 14 studies that looked at the link between stroke and migraine. They discovered that all migraine sufferers -- regardless of gender or whether the migraines were accompanied by an aura -- had twice the risk of stroke as people who didn't get migraines. They also found that women younger than 45 who take oral contraceptives and suffer migraines were more than eight times as likely as non-sufferers to have a stroke.
Although it is double that of the general population, the stroke incidence for migraine sufferers still is only 2 per 100,000 people.
Stroke is triggered by the formation of blood clots in the brain, and migraines are caused when blood vessels constrict. "This reduced blood flow in migraine sufferers may also be a cause of stroke," says Etminan. "And migraine patients may be more prone to blood clotting, which predisposes them to future strokes. It's an interesting piece of the puzzle, but more research needs to be done."
The study appeared in the Dec. 13 issue of the British Medical Journal Online First.