In the first review of its kind, researchers in Canada and the US looked at 14 studies which investigated an association between stroke and migraine. They found that the risk of stroke for migraine sufferers was 2.16 times that for non-sufferers.
Those who have interrupted vision from light affects (aura) with their migraine were at slightly higher risk than those without; 2.27 times as likely to suffer a stroke compared to 1.86.
Three of the studies showed that women migraine sufferers who are also taking the oral contraceptive pill were up to eight times more likely to suffer a stroke than those not taking the pill. Though these results were at odds with other studies which suggest a smaller degree of increased risk for women in this category – indicating the need for much more research in this area.
The increased risk of stroke is probably down to the reduced blood flow to the brain which usually occurs in a migraine, suggest the researchers.
Migraine is the most common form of headache in young adults, with as many as a quarter of women in their mid to late thirties suffering the condition. The link between migraine and stroke established in this review raises new questions about whether these two conditions share similar risk factors, which must be further researched. In particular, much more investigation is needed into risk factors for migraine sufferers who are taking oral contraceptives, they conclude.