More than half a million people died from strokes linked to high and low temperatures in 2019 alone, a new study has found. This number is expected to increase as the world warms due to human-induced climate change.
The study, published Wednesday in the medical journal Neurology, found that the number of strokes attributable to high and low temperatures has increased worldwide since 1990. Men suffered more strokes due to extreme temperatures than women, but the condition affected people in all age groups.
For this study, researchers examined temperatures and strokes in 204 countries and territories. Researchers from Xiangya Hospital Central South University in China built a model using global data on illness, death and disability, and climate data capturing temperatures, cloud cover and weather variables.
The authors of the study noted that as the population ages and grows, the number of people suffering strokes also increases, but this does not explain everything. “Non-optimal temperatures” made a difference: The number of people suffering strokes due to hot and cold weather increased and was significantly higher in 2019 than in 1990.
It was the low temperatures that caused the number of hits to increase in 2019. Although this may seem counterintuitive in terms of global warming, cold weather also brings climate change. Warmer temperatures over land interfere with the polar vortex (the dense mass of cold air around the poles) and can lead to lower temperatures when it weakens.
Currently, stroke deaths due to extreme temperatures are disproportionately concentrated in regions where people live in poverty and health systems are fragile, such as in Africa. The rapidly increasing burden of stroke in Central Asia due to high temperatures “also requires special attention,” the study said.
The burden of strokes caused by high temperatures is “increasing rapidly” as the planet warms, and the number will rise “sharply” in the future, the study said.
Higher temperatures are already here. Last year was the warmest since scientists began recording global temperatures in 1850, and temperatures are expected to break more records in the near future. This March was the hottest March in history.
D., an associate professor of medicine at Harvard Medical School who did not work on the new research. Mary Rice said the findings were important.
“I think this group has done a really good job of taking a global approach by looking at historical data and bringing attention to a health issue that I think doesn’t get a lot of attention,” said Rice, a pulmonologist at Beth Israel Deaconess. Medical Center in Boston. “The total burden of people dying from heat-induced stroke is actually a very large number.”
Rice recently published a study in the journal Frontiers in Science that found that climate change is also leading to an increasing number of immune-mediated diseases such as allergies, asthma, autoimmune diseases and cancers. Rice’s work suggests that multi-level mitigation actions are urgently needed to reduce emissions and improve air quality while tackling the climate crisis.
Without immediate global action, the world will face a much greater disease burden, he said.
‘It’s happening everywhere’
Stroke is already an important health problem. Previous research has shown that it is the third leading cause of disability worldwide and one of the leading causes of death.
The new study was not designed to show why the extreme temperatures that come with the climate crisis are causing so much paralysis. Other research has shown that when temperatures are extremely high, it is difficult for the body to regulate and cool itself through sweating. This can lead to what doctors call a hypercoagulable state, in which blood clots more easily and increases the risk of stroke. People can also become dehydrated, which can force the heart to work too hard, also increasing a person’s chances of having a stroke or heart attack.
Extremely cold temperatures can also cause someone to have a stroke. When the body is exposed to cold, the skin’s cold receptors are stimulated, which triggers the network of nerves known as the sympathetic nervous system that controls the body’s fight or flight response. This causes vasoconstriction, the narrowing of blood vessels in the skin, arms, and legs, which can lead to increased blood pressure and potentially stroke.
Dr., a neuroscientist affiliated with the University of Colorado Climate and Health Program. Ali Saad said he has already talked about this incident with paralyzed patients, reminding them how dangerous extreme temperatures, especially heat, can be. He said he would take their phones and add weather alerts so they would be aware of when the temperature would rise.
“I tell them, ‘I’m worried you’re going to overheat, and there are things we can do to prevent both paralysis and worsening climate change,'” Saad said.
Saad did not work on the new study but said he hoped this latest research would attract the attention of global leaders and influence public policy.
“Extreme weather conditions, or more specifically extreme temperatures, are known to be a risk factor for stroke, but what this study adds is that it is the first study to examine this condition on a global scale,” Saad said. “When people think of pollution or heat when it’s related to health outcomes, stroke or anything else, they often think of low- and middle-income countries, but this is happening across the board and is expected to get worse.”
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