Migraine headaches may cause progressive brain damage and increase the risk of stroke, research suggests.
Migraines affect one in 10 people
Scientists have found evidence people who suffer from migraine have damage in an area of the brain called the cerebellum.
And the more frequent the migraine attacks, the higher the risk of damage.
The research, by a team from Leiden University in The Netherlands, is published in the Journal of the American Medical Association.
The researchers say their findings seem to refute the commonly held perception that migraine is essentially a trivial problem with transient symptoms.
They hope their work may lead to better treatments, which may prevent cumulative damage to the brain.
Lead researcher Dr Mark Kruit told BBC News Online: "Migraine may be a more serious disorder, not just a headache."
It is estimated that 12% of the population of Western Europe and the US suffer from migraine attacks each year.
The study focused on 435 people. Some were free of migraine, some suffered standard attacks and some had a form called migraine with aura.
The study showed that patients who experience migraine with aura were at much higher risk for tissue damage - known as infarcts - in the cerebellar region of the brain than were patients who experienced migraine without aura.
The risk of damage was more than seven times greater in patients with migraine than in those who were free from the headaches, and that risk increased as the number of attacks increased.
The highest risk was in those patients with migraine with aura who had an attack frequency of one attack or more per month.
Women with migraine - but not men - also showed evidence of brain damage in the white matter of another area of the brain called the cerebrum.
Writing in the journal, the researchers say: "These findings indicate that adult migraine patients may be at increased risk of clinical stroke, and that the real extent of brain injury in migraine patients from the general population may have been underestimated."
They say further studies are needed to confirm the results, but it may be that migraine guidelines should emphasis the need for early prevention to decrease the risk of brain lesions.
Dr Andrew Dowson, medical advisor to the Migraine Action Association, told BBC News Online that previous research had not shown evidence of tissue damage in the cerebellum at anything other than background levels in migraine patients.
He said: "We are surprised with the findings. We also feel that we should not alarm the public until more is known.
"Having said that if this turns out to be true, the whole view of migraine will change.
"It is currently a self-limiting, quality of life affecting disorder, with treatment directed at reducing disruption.
"But if these findings are true it becomes potentially a progressive disease with entirely different management targets."
Migraines are a complex group of symptoms characterised by unpredictable attacks of typically moderate to severe, usually one-sided, throbbing headaches.
They are aggravated by routine physical activity such as climbing stairs, last from four to 72 hours, and are accompanied by nausea, vomiting, and sensitivity to sound and light.