Deaths and disability due to stroke around the world are increasingly linked to temperature changes driven by climate change, a new analysis of global data over three decades has found.

In 2019, there were over 5.2 lakh stroke deaths linked to non-optimal temperatures, the study, published in the journal Neurology, found.

While the majority of these stroke deaths—more than 4.7 lakh—were due to lower than optimal temperatures, researchers also found that number of deaths from stroke linked to higher than optimal temperatures had increased, when compared with 1990. They associated optimal temperatures with the lowest death rates.

The burden of stroke "due to high temperature has increased rapidly, especially among people aged older than 10 years, and was disproportionately concentrated in low Socio-demographic Index (SDI) regions such as Africa," they wrote in the study.

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In India, there were nearly 33,000 deaths from stroke attributable to non-optimal temperatures, 55 per cent of which (roughly 18,000) were attributable to higher than optimal temperatures and 45 per cent (roughly 15,000) to lower than optimal temperatures, the researchers found.

"Dramatic temperature changes in recent years have affected human health and caused widespread concern," study author Quan Cheng of Xiangya Hospital Central South University in Changsha, China, said.

The researchers said that ageing too was a key factor in the increase in burden of stroke attributable to temperature changes.

The team further found that the death rates from stroke due to non-optimal temperatures were higher in men at 7.7 per 1 lakh population, compared to women at 5.9 per 1 lakh population.

Regionally, central Asia was found to have the highest death rate for stroke linked to non-optimal temperatures with 18 per 1 lakh population.

The team said more research was needed to determine how temperature changes impact stroke and to target solutions to address health inequalities.

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"Future research should aim to reduce this threat by finding effective health policies that address potential causes of climate change, such as the burning of fossil fuels, deforestation and industrial processes," said Cheng.

For their analysis, the researchers looked at datasets from the Climate Research Unit Gridded Time Series, the World Bank, and the Global Burden of Diseases study for estimating the spread of stroke burden in 204 countries and territories around the world.