A new review of studies by researchers working with the World Stroke Organization finds that environmental changes driven by climate change may increase the risk of both having a stroke and dying from one.
The research links extreme temperatures, sudden temperature swings, humidity, air pressure changes, wildfires, and dust storms to higher stroke incidence. While most evidence shows association rather than direct causation, the pattern is consistent and biologically plausible.
Anna Ranta, senior lead author and researcher at the University of Otago, explained that hot temperatures can cause dehydration, thickening the blood and raising the risk of blocked vessels. Humidity and air pressure changes can increase blood pressure, a major stroke cause. Weather extremes occurring together can have an additive effect, further elevating risk.
Older adults, people with metabolic disorders, and those in colder or lower-income settings appear most vulnerable.
The World Stroke Organization also highlights air pollution as a major factor: particulate matter enters the bloodstream via the lungs, damaging blood vessel walls and potentially causing blocked or ruptured brain arteries. Environmental risk factors, primarily air pollution and lead exposure, account for about 37% of the global stroke burden.
Because climate change and air pollution share a common source-burning fossil fuels-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.