Good news for chronic migraine sufferers: even the most severe forms of these blindingly painful headaches do not cause damage to the brain.
"It is almost always the first question that migraine patients ask," said Christophe Tzourio, a doctor and researcher at the Universite Pierre et Marie Curie in Paris, and the main architect of a study published online this week in the British Medical Journal.
"Today we can provide an answer: there's nothing to worry about," he told AFP.
Migraines are acutely debilitating headaches - sometimes with an "aura", in which patients have the impression of seeing through frosted glass - that strike around one out of nine adults.
The causes remain uncertain, but are known to involve a link with blood vessels in the brain.
Earlier research using magnetic resonance imaging technology showed that people with a history of full-on migraines are more likely to incur tiny lesions to microvessels inside the brain.
Such ruptures result from a deterioration of the small cerebral arteries that supply blood to so-called white matter, which facilitates the flow on information across different parts of the brain.
The same type of lesions are more common in elderly people, diabetics and hypertension sufferers.
In large quantities, they have been linked to depression, an increased risk of stroke, neurodegenerative diseases such as Alzheimer's, and impaired memory and reasoning.
Tzourio and colleagues wondered if migraine patients are more likely to show some of these symptoms, so they tested the cognitive abilities of more than 800 over-65 seniors living in Nantes, western France.
Nearly 15 percent of the volunteers had suffered from migraines over the course of their lives.
On average their scores were indistinguishable from the others. Even seniors who had endured the most debilitating type of migraine, with aura, showed no cognitive damage.
"This is a very reassuring result for the many people who suffer from migraine," said co-author Tobias Kurth, also a researcher as Universite Pierre et Marie Curie.
"In spite of the increased presence of lesions of the brain microvessels, this disorder does not increase the risk of cognitive decline," he said in a press release.