New research from the US found that severe headaches such as migraine were linked to changes in weather, particularly to increased ambient temperature and to a lesser extent lower barometric pressure.


The study was the work of first author Dr Kenneth Mukamal, a physician in the Division of General Medicine and Primary Care at Beth Israel Deaconess Medical Center (BIDMC), in Boston, Massachusetts, and colleagues, and is published online in the 10 March issue of the journal Neurology.

About 18 per cent of women and 6 per cent of men in the US report having migraine headaches, with young and middle aged adults particularly affected, wrote the researchers.

And while some small studies have suggested various aspects of weather and air pollution may trigger headaches, their conclusions have been inconsistent, they added.

Mukamal and colleagues carried out a study of 7,054 patients who attended the BIDMC emergency department between May 2000 and December 2007. Of these, 2,250 had migraine and 4,803 had tension or unspecified headache as their primary discharge diagnosis.

The study was a "case crossover" design, where for each "case" or patient, the levels of pollutants and other weather variables on the day they attended the hospital were compared directly to corresponding levels on the days before and in the weeks after the visit.

Mukamal and colleagues used meterological and pollutant monitors to measure air temperature, barometric pressure, humidity, and a range of pollutants such as fine particulate matter, black carbon, and nitrogen and sulfur dioxides.

The results showed that: There was a linear direct relationship between higher mean ambient temperature in the 24 hours before a hospital visit and acute risk of headache.
For a 5 deg C increase in temperature (about 9 deg F) there was a 7.5 per cent rise in acute risk of headache (odds ratio [OR] of 1.075; 95 per cent confidence interval [CI], 1.021-1.033; p = 0.006).