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).Lower barometric pressure 48 to 72 hours prior to emergency room visits was also linked to increased risk of headache, but to a much lesser degree (OR 0.939 per 5 mm Hg; 95 per cent CI, 0.902-0.978; p = 0.002).

Mukamal and colleagues concluded that:

“Higher ambient temperature and, to a lesser degree, lower barometric pressure led to a transient increase in risk of headache requiring emergency department evaluation.”

There was no evidence that air pollutants were linked to the onset of headache, but they said they could not rule out a smaller effect similar to that previously reported for stroke and other cardiovascular events.

Mukamal said in a press statement that their findings are consistent with the notion that severe headaches can be triggered by environmental factors.

“These findings help tell us that the environment around us does affect our health and, in terms of headaches, may be impacting many, many people on a daily basis,” he added.

Mukamal suggested that patients talk with their doctors to try and find out what triggers their headaches. Although we can’t change the weather, the doctor might be able to prescribe medication that could help avert headaches that follow weather changes.

“On a population basis, we need to be concerned about incremental temperature rises anyhow, and should advocate for responsible environmental management,” said Mukamal.

“The annual cost attributed to migraines is estimated at 17 billion dollars, millions of people are adversely affected and the public health implications may be enormous,” he added.

The National Institute of Environmental Health Sciences and the US Environmental Protection Agency funded the study.

“Weather and air pollution as triggers of severe headaches.”
Kenneth J. Mukamal, Gregory A. Wellenius, Helen H. Suh, and Murray A. Mittleman.
Neurology 2009 72: 922-927.
Published online 10 March 2009.

Click here for Abstract.

Sources: Journal article, Beth Israel Deaconess Medical Center.

Written by: Catharine Paddock, PhD