Environmental changes made worse by climate change, including extreme temperatures, sudden temperature swings, humidity, air pressure, wildfires, dust storms and sandstorms, may be linked to a higher risk of stroke, according to new research. Researchers working with the World Stroke Organization examined published studies looking at links between stroke and climate-related environmental changes.They found that an increasingly unstable climate may raise the risk of both having a stroke and dying from one.Researchers cautioned that most of the evidence shows associations, rather than proving that climate-related weather events directly cause strokes. However, they said the overall pattern of findings was consistent and biologically plausible. “Hot temperatures can cause dehydration, ‘thickening’ the blood and raising the risk of blocked blood vessels, while humidity and air pressure changes can increase blood pressure, an important cause of stroke,” said Anna Ranta, senior lead author of the review and researcher at the Department of Medicine at the University of Otago, Wellington, New Zealand.Ranta said weather extremes occurring together, such as extreme heat and drought, or cold, humidity and wind, can have an additive effect, increasing the risk of stroke and death even further.The research found that some groups appear to be at greater risk, including older adults, people with metabolic disorders, and those living in colder or lower-income settings, where both cold and heat extremes can contribute more heavily to the stroke burden.The World Stroke Organization has also highlighted air pollution as a major factor in stroke risk.Its most recent Global Stroke Fact Sheet found that environmental risk factors, primarily air pollution and lead exposure, account for approximately 37% of the global stroke burden.“The particulate matter of the ‘air pollutants’ enters the bloodstream via the lungs and cause damage to blood vessel walls. This can result in blocked and ruptured brain arteries and cause a stroke.”Because climate change and air pollution share a common source in the burning of fossil fuels, the World Stroke Organization said reducing greenhouse gas emissions could help lower climate-related stroke risks and protect brain health. Stroke is the third leading cause of death and disability globally, with 11.9 million new cases in 2021 and 1 in 4 adults at risk in their lifetime, according to the World Health Organization.