Stroke Risk Increases with Changes in Temperature and Cold Weather

Past research has shown conflicting evidence between the relationship of stroke risk and weather. A study conducted at Yale University hopes to establish a relationship and encourage further research on the subject.

The study surveyed 157,000 stroke patients who were admitted to hospitals between 2009 and 2010, also taking into account daily temperatures and dew points. The Yale researchers presented their study today at the American Stroke Association International Stroke Conference in San Diego.

Scientists knew before that humidity was a factor in stroke risk, but the Yale study found that cold weather as well as big daily temperature swings also play a role. Specifically, they found that a higher percentage of strokes occurred in the winter as well as during temperature swings of five degrees Fahrenheit in a given day. On a positive note, stroke risk was found to decrease when the temperature increased by five degrees Fahrenheit in between days.

The evidence was not definitive, since the stroke risk percentages were very small (specifically between a 2% and 4% drop or rise), but Judith Lichtman, an epidemiologist at the Yale School of Public Health, believes it should be a cause for future concern.

"Maybe some of these meteorological factors serve as a trigger," said Lichtman, in this ABC News article. And with global climate change and extreme weather like this week's freak storm in the South, "this could be increasingly important," she added.

Although the evidence wasn't significant enough to arrive at a conclusion for when stroke risks were the highest, cold weather proved to affect blood pressure, which is a determining factor in suffering a stroke. Cold temperatures can contribute to constricting blood vessels, which can raise blood pressure. The cold can also cause respiratory illnesses that may raise stroke risks.

The presence of lower temperatures and higher dew points revealed a slightly higher percentage in stroke hospitalization rates. Again, the evidence is not plentiful enough to draw concrete conclusions, but it may become more of an issue as climate change continues to worsen.

To read more about this study, visit this LiveScience article.