Study: Cold, humidity, temperature swings increase stroke risk


Minnesota has traditionally had one of the lowest stroke rates in the nation, but a new study suggests that weather conditions common in the state – including humidity, daily temperature swings and the all-too-familiar cold – can increase the risk of stroke.

Researchers analyzed climate trends and hospital records on a sample of 134,510 American adults, and they found that those meteorological factors seem to be tied to more people turning up at the hospital with strokes, the Associated Press reports.

Authors of the study from Yale, Harvard and Duke universities on Wednesday unveiled the results of their study at the American Heart Association's International Stroke Conference in San Diego. The report is the most detailed study yet on the topic.

Of interest to winter-weary Minnesotans, the researchers note: When the average temperature goes up one degree, the odds of being hospitalized because of a stroke go down 0.86 percent, and the odds of dying from a stroke go down 1.1 percent.

Of course, that works the opposite way too. The risk of stroke goes up for every degree the thermometer goes down, according to this analysis.

Why does the temperature matter? Researchers say blood vessels constrict in cold weather, which can raise blood pressure, and the extreme cold can trigger a stress reaction in the body that increases the heart's workload and makes blood stickier and more likely to clot, the AP reported.

Minnesota summers don't offer shelter from the disheartening facts presented Wednesday: Daily temperature fluctuations and higher dew points increase stroke hospitalization, too. High humidity raises the risk for clots and body stress, the researchers said.

So is it time to move to San Diego? Nah. Minnesota actually has among the very lowest stroke rates in the nation, according to a 2012 Centers for Disease Control and Prevention report.

Notably – and this seems contrary to the report findings – geography also acts as a stroke risk indicator, and the warm-weather Southeast has some of the highest stroke death rates in the nation, the CDC says (see county-by-county map).

And here's more context: Lots of other factors increase stroke risk, including unhealthy life choices. High blood pressure, high cholesterol, and smoking are major risk factors for stroke (nearly half of Americans have at least one of those three), the CDC reports.

Other indicators of stroke risk: age, family history, race and ethnicity, the CDC says.

Strokes kill about 130,000 people in the U.S. every year, making it the No. 4 leading cause of death in the nation, behind heart disease, cancer and chronic lower respiratory diseases.

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