Women who suffer from migraines are four times more likely to develop Alzheimer's disease in later life, a new study suggests.
Researchers at the University of Waterloo in Canada asked 679 people aged 65 and over about their history of migraines, then followed their progress for five years.
During that time, 51 people (7.5 per cent) developed dementia, and 34 out of those 51 people had Alzheimer's disease, which is a degenerative disease of the brain.
The study data showed that 23.5 per cent of people with Alzheimer's had a history of migraines. Alzheimer's sufferers were more than four times more likely to have had migraines, and those with dementia were almost three times more likely to have had them.
Experts believe that the severe headaches, which affect one in five women and almost one in 12 men, can cause inflammation in the brain, leading to neurological damage which may cause memory loss.
The research, published in the International Journal of Geriatric Psychiatry, shows that those who suffer from the debilitating headaches could be monitored more closely for signs of dementia or Alzheimer's in an effort to detect the disease much earlier.
The findings may also help improve future researchers' understanding of the biology of Alzheimer's disease and dementia.
Dr Suzanne Tyas, senior author of the study, said: "We don't yet have any way to cure Alzheimer's disease, so prevention is key. Identifying a link to migraines provides us with a rationale to guide new strategies to prevent Alzheimer's disease."