Stroke Risk and the Weather

Stroke risk and the weatherLooking not only at deaths but also hospitalizations, a recent study lends support to the idea that the weather may be tied to stroke risk. For strokes caused by clots, low temperatures, large temperature fluctuations, and higher humidity appear to raise the risk of having a stroke. Researchers found that each 5-degree temperature increase raised the chance of being hospitalized for a stroke by 6 percent. Each 5-degree rise in the dew point (used to calculate the humidity level) raised the risk of being hospitalized by 2 percent. As the temperature gets warmer, the risk of stroke hospitalization falls 3 percent for every 5 degrees. It may be that high humidity causes dehydration, which can stress the body and raise the risk of clots. In cold weather, blood vessels constrict, which can raise blood pressure and perhaps a stress reaction that makes blood more likely to clot. And it’s not just the weather that may be influential. Researchers in New Zealand found that more people have strokes after solar storms that are directed at Earth. Sudden disruptions of blood flow to the brain appear to happen nearly 20% more often on days with geomagnetic storms. While people usually have strokes around age 70, the link between the geomagnetic storms and stroke was stronger for those under 65. There was no speculation as to why there might be such a link.