Researchers warn that temperature may increase the risk of stroke, especially when it’s colder.

A recent study finds people are more likely to have a stroke, and die from it, when there are rapid changes in the temperature and higher humidity.  Warmer weather, on the other hand, reduces the risk of needing to visit the hospital after a stroke, and increases the chances of survival.  In fact, the study found that with each one degree increase in average temperature, the risk for stroke hospitalization and death decreased by one percent.

“Weather is not something people would typically associate with stroke risk; however, we’ve found weather conditions are among the multiple factors that are associated with stroke hospitalizations,” said Judith Lichtman, study leader and associate professor in Epidemology at the Yale School of Public Health.

The study suggests that meteorological factors, including daily fluctuations in temperature at humidity, may be linked to increase stroke hospitalizations.  Cooler temperatures may trigger strokes because exposure to cold conditions has many effects on the body ranging from increased blood pressure and constriction of blood vessels, to the clotting tendency of platelets

“People at risk for stroke may want to avoid being exposed to significant temperature changes and high dew point and, as always, be prepared to act quickly if they or someone they know experiences stroke signs and symptoms,” said Lichtman.

Lichtman’s team identified a sample group of 134,510 people across the nation that are 18 and older and who have been admitted to hospitals between ’09-’10 because of a stroke.  The team then compared that information with data on the weather, including temperature and dew point.  The team found that larger daily temperature changes and changes  higher average humidity is associated with higher stroke hospitalization rates.  Lower average annual temperatures can be linked with stroke hospitalizations and death.

“Future research is needed to better understand the cause and effect of changes in weather conditions, as well as to explore potential mechanisms for this association,” said Lichtman.