From Nature:
A migraine is not just a headache, it is an über-headache — a pounding, queasy, searing pain that can incapacitate its victims for hours on end. And as if the pain weren’t bad enough, sufferers were also thought to show diminished memory and verbal skills. But new research now suggests that although migraines are sometimes associated with diminished cognitive skills, sufferers may in fact show less memory loss as they age than those who are migraine-free.
More than 28 million people in the United States suffer from migraines, and women are three times more likely than men to have the condition. The cause is still unknown, and different theories have blamed nervous-system malfunctions, chemical imbalances, over-reactive blood vessels, or a combination of factors. Meanwhile, attempts to catalogue the damage wrought by a lifetime of migraine attacks have met with conflicting results. Some studies suggest that migraineurs have poorer memories and less verbal ability than those without the condition, whereas other studies show no difference at all between sufferers and non-sufferers.
Exactly why the migraineurs would be more protected from cognitive decline remains a mystery.
More here.