It has long been known that there is an association between migraine headaches and the risk of stroke. This association is strongest in migraine sufferers who experience aura prior to the headache itself. The aura consists of one or more unusual symptoms - such as flashing lights, confusion, or even partial paralysis - preceding an actual migraine attack. It is thought to be the result of vascular constriction or spasm within the brain. Teri Roberts, Headache Guide at About.com, has an excellent description of the phases of migraine, here.
Because aura is thought to represent "hyperactive" blood vessels, and because it is associated with an increased incidence of stroke, researchers have wondered whether migraine in general, or aura in particular, might produce an excess risk for other vascular events. A study published in the July 19 issue of the Journal of the American Medical Association shows that this is indeed the case.
Investigators studied over 27,000 women enrolled in the Women's Health Study, all of whom had no evidence of cardiovascular disease at the time of enrollment. Of these, 5125 had a history of migraine, and 1434 reported having aura prior to their migraine attacks. During the course of the study, women with aura (but not those with migraine unaccompanied by aura) had a significantly increased risk of cardiovascular events (such as heart attack, angina, coronary artery disease requiring bypass or angioplasty/stenting, or cardiovascular death). Investigators attributed an additional 18 cardiovascular events per 10,000 women per year to migraine with aura.
This study does not answer the question of why there is increased cardiovascular risk in people who have migraine with aura. Several possibilities exist, including the hyperactive blood vessels that accompany aura, the release of substances into the blood vessels that can trigger blood clotting or accelerated plaque formation, or a genetic link between migraine with aura and cardiovascular disease. What this study does indicate is that, if you have migraine attacks with aura, you should pay special attention to modifying cardiovascular risk factors that you can control, like lipids, inactivity, obesity, hypertension and smoking.
New studies will be required to determine whether controlling migraine attacks with medication might itself reduce the cardiovascular risk.
Kurth T, Gaziano JM, Cook NR, et al. Migraine and risk of cardiovascular disease in women. JAMA2006; 296:283-291.