Research links weather with migraine

New York, March 10: The risk of migraine can upsurge by 7.5 percent for every five degree Celsius increase in temperature, researchers from Beth Israel Deaconess Medical Center, who studied more than 7,000 patients over a 7-year period, revealed yesterday.

The study used weather records and air pollution readings from a monitor on the roof of the Countway Library of Medicine and matched them to headache diagnoses from emergency doctors.

According to their report, for temperature increase of 9 degrees Fahrenheit (5 degrees Celsius) in 24 hours, there was a 7.5 percent higher risk of severe headache.

Low barometric pressure was linked with a small increase in risk. For every 5 millimeters the barometric pressure reading fell over 72 hours, there was a 6 percent higher risk of headache.

There was no strong association with air pollution though. But the automobile exhaust pollutant nitrogen dioxide did show a borderline effect on non-migraine headaches.

Lead author of the study, Dr. Kenneth Mukamal, said in an interview, "Our study was not big enough to look at air pollution definitively. What we did see is that there are environmental triggers to headache."

Initially, two small Canadian studies tried to compare weather and headaches but had contradictory results. "Ours was one of the very first large-scale efforts to evaluate environmental triggers for headache, particularly for severe headaches.

“The study was based on hospital diagnoses rather than on patients' recall of a headache was strength of the study,” Mukamal said.

But according to Dr. Deborah Friedman, a member of the American Academy of Neurology and a neurologist at the University of Rochester, “The diaries kept by headache sufferers would tell researchers when their symptoms began.”

Friedman disagreed with the research and further faulted the hospital headache diagnostic codes as not specific enough and noted that the patients' entire charts were not examined.

"To me it means you can't extrapolate and say that barometric pressure and air temperature is a migraine trigger," she said in an interview.

"All you can say is a trip to the emergency department for patients who had any kind of headache was perhaps related to a small rise in temperature and lower barometric pressure."

The study was funded by the National Institute of Environmental Health Sciences and Environmental Protection Agency and was published in March 10, issue of journal Neurology.