High temperatures and factors such as obesity ‘driving global rises in stroke’

Air pollution, high temperatures, and risk factors such as obesity and high blood pressure are driving global increases in stroke, research suggests.

Although stroke is very preventable and treatable, latest figures estimate there are 12 million cases and more than seven million deaths from stroke each year.

However researchers say there are “tremendous opportunities” to alter the trajectory of stroke risk for the next generation, because so many risk factors can be addressed.

Between 1990 and 2021, the number of people who had a new stroke rose by 70%, and the number who died from a stroke increased by 44%, according to the findings.

Experts suggest this increase is due to both population growth and people living longer, as well as a substantial increase in people’s exposure to environmental and behavioural risk factors.

A stroke is a serious life-threatening medical condition that happens when the blood supply to part of the brain is cut off.

The findings of the new analysis from the Global Burden of Disease, Injuries, and Risk Factors Study (GBD) indicate the condition is the third leading cause of death worldwide, after coronary heart disease and Covid-19.

The study, published in The Lancet Neurology journal and presented at the World Stroke Congress in Abu Dhabi, found that more than three-quarters of those affected by strokes live in low- and middle-income countries.

Co-author Dr Catherine Johnson, lead research scientist at the Institute for Health Metrics and Evaluation (IHME) at the University of Washington in the US, said: “With 84% of the stroke burden linked to 23 modifiable risk factors there are tremendous opportunities to alter the trajectory of stroke risk for the next generation.

“Given that ambient air pollution is reciprocally linked with ambient temperature and climate change, the importance of urgent climate actions and measures to reduce air pollution cannot be overestimated.

“And with increasing exposure to risk factors such as high blood sugar and diet high in sugar-sweetened drinks, there is a critical need for interventions focused on obesity and metabolic syndromes.

“Identifying sustainable ways to work with communities to take action to prevent and control modifiable risk factors for stroke is essential to address this growing crisis.”

The condition is preventable, but the research suggests 84% of strokes in 2021 were linked to 23 risk factors that can be addressed.

These included air pollution, excess body weight, high blood pressure, smoking, and physical inactivity.

The study suggests that the contribution of high temperatures to poor health and early death due to stroke has risen 72% since 1990.

For the first time, the study reveals the contribution of particulate matter air pollution to a fatal brain bleed.

It contributed to 14% of the death and disability caused by this serious stroke subtype, with the study indicating it is on a par with smoking.

In order to reduce the burden of stroke, effective, accessible, and affordable measures to improve stroke surveillance, prevention (with the emphasis on managing blood pressure, lifestyle, and environmental factors), care, and rehabilitation need to be urgently implemented across all countries, the experts say.

Lead author Professor Valery L Feigin, from Auckland University of Technology in New Zealand, said: “New, proven effective population-wide and motivational individual prevention strategies that could be applied to all people at risk of having a stroke, regardless of the level of risk, as recommended in the recent Lancet Neurology Commission on Stroke should be implemented across the globe urgently.”

The study also found that progress has been made in reducing the global stroke burden from risk factors linked to poor diet, air pollution, and smoking.

Health loss due to diets high in processed meat and low in vegetables fell by 40% and 30%, respectively, particulate matter air pollution by 20%, and smoking by 13%.

This indicates that strategies to reduce exposure to these risk factors, such as clean air zones and public smoking bans, have been successful.