Inclement Weather Linked to Headaches

March 10, 2009 -- As if there weren't already enough reasons to curse fickle weather: a new study confirms it can trigger headaches.

For the 32 millions Americans who suffer from migraines, this may not come as a surprise. Weather-related headaches are a common complaint, and several smaller studies have hinted that variables like temperature and barometric pressure may play a role in causing painful outbreaks.

Now a survey of 7,054 patients admitted to emergency rooms in the Boston, Mass. area has confirmed the suspicion. For every 5 degree Centigrade (9 degrees Fahrenheit) increase in temperature, both migraine and non-migraine headache risk went up 7.5 percent over the next 24 hours.

For every 5 millimeters (.20 inches) of mercury drop in pressure, there was also a 6 percent increase in headache risk, though the effect showed up two to three days later. Drops in pressure typically happen as stormy weather moves in.

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Lead author Kenneth Mukamal of Beth Israel Deaconess Medical Center said the results suggest that even relatively minor changes in weather can have big impacts on people's health.

"This is a global issue; weather affects every single human," he said. "When temperature goes up and pressure goes down, everyone is exposed to a pretty debilitating disease that affects not just the old and sick, but young and healthy people, too."

But why this effect happens is a mystery. Blood pressure is known to decrease in warmer months, but the study found no difference between headaches associated with temperature spikes in the winter versus those occurring during the summer. Mukamal also speculated that atmospheric pressure changes may upset the sinuses and lead to headaches.

"I wish I knew why this happens," he said. "It clearly affects your internal circuitry."