Headache and migraine linked to hot weather, air pollution

Higher temperatures, and to a lesser degree, lower barometric pressure, contribute to severe headaches, revealed by researchers in issue of the journal Neurology.

Although large numbers of headache sufferers, particularly individuals who struggle with migraines, attribute their pain to the weather, there has been little scientific evidence to back up their assertions.

Now, a study of more than 7,000 patients, led by researchers at Beth Israel Deaconess Medical Center (BIDMC), provides some of the first large-scale data on how environmental conditions — weather, as well as air pollution — influence headache pain.

“Migraine headaches affect a large proportion of the population,” notes Kenneth Mukamal, MD, MPH, the study’s first author and a physician in the Division of General Medicine and Primary Care at BIDMC. “Approximately 18 percent of women and 6 percent of men in the U.S. report having migraine headaches, particularly young and middle-aged adults.”

Knowing that migraines can be set off by “triggers,” including certain foods, alcohol, stress and hormones, Mukamal and his coauthors decided to study whether environmental factors were also acting as headache triggers.

“Air temperature, humidity and barometric pressure are among the most frequent reasons that people give for their headache pain,” explains Mukamal, who is also an Associate Professor of Medicine at Harvard Medical School. “But none of these reasons have been consistently verified. We wanted to find out if we could verify this ‘clinical folklore.’ We also wanted to determine whether air pollutants trigger headaches, much as they have been found to trigger strokes.”

The findings showed that of all of the environmental factors considered, higher air temperature in the 24 hours prior to the patient’s hospital visit was most closely associated with headache symptoms, with a 7.5 percent higher risk of severe headache reported for each temperature increase of 5 degrees Celsius (approximately 9 degrees Fahrenheit). To a lesser degree, lower barometric pressure 48 to 72 hours prior to patients’ emergency room visits also appeared to trigger headache. The researchers found no evidence that air pollutants influenced the onset of headache, but could not rule out a smaller effect similar to that previously seen for stroke.

“Certainly our results are consistent with the idea that severe headaches can be triggered by external factors,” says Mukamal.

This research was supported by grants from the National Institute of Environmental Health Sciences and the U.S. Environmental Protection Agency.

Source: Beth Israel Deaconess Medical Center, USA



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