LONDON -- Migraine patients may face a significantly increased risk of asthma as well as blinding headaches, according to a major British study released on Monday.

Researchers at St. George's Hospital Medical School, London, compared the prevalence of asthma in nearly 65,000 migraine patients with an equal number of patients without migraine.

The relative risk of asthma in patients with migraine was raised by 59 percent, Professor David Strachan and colleagues reported in **** The British Journal of General Practice ****.

"This large case-control study provides evidence of an association between migraine and asthma," Reuters quoted Strachan as saying.

The study had "huge statistical power" although it was still possible that confounding factors had skewed the findings.

"However if the association is real, its elucidation may help the understanding of disease mechanisms shared by migraine and asthma," they said. "A shared functional abnormality of smooth muscle in blood vessels and airways offers a plausible explanation."

Earlier studies also suggest a link between migraine and wheezing illness. The United States Collaborative Perinatal Project found that asthma was more common in children of mothers with migraine than in those whose mothers were migraine-free.

More recently, analysis of a 1958 British Birth Cohort identified an increased incidence of asthma among subjects with a prior history of migraine.