Having someone reliable for help is one of the most important factors in reducing the risk of an older person dying during a heatwave, Tsinghua researchers find.
Recent findings show it’s not old age itself, but functional impairments, such as poor mobility, a dependency on help, cognitive deficits, and social isolation, that are the real drivers of heatwave mortality.
“A new understanding is emerging that recognizes that two people of the same chronological age can have vastly different levels of vulnerability based on their functional status,” explains public health expert, John S. Ji, who leads the team that made the finding at Tsinghua’s Vanke School of Public Health. “Older adults who maintain good mobility, cognitive function, and strong social networks are significantly less at risk.”
Researchers have found that functional impairments, such as poor mobility, cognitive deficits, and social isolation, drive up the risks of heatwave mortality in older people. But they also suggest interventions that could reduce the impact of heatwaves on vulnerable populations.
The epidemiological analysis, published in Nature Medicine, assessed the daily heatwave exposure of 13,527 participants between 2008 and 2018 in China who participated in a longitudinal study on health status and quality of life of people aged 65 and older. The study included 3,249 deaths that occurred during summer (May to September).
The heat is on
Due to climate change, heatwaves are increasing in frequency and intensity, leading to heightened projections of deaths worldwide. Mortality risk on heatwave days roughly doubles for the average adult, and it poses an even more significant danger to China’s growing elderly population, explains Ji.
Heatwave days are those of abnormally hot temperatures for a given location, and Ji took at these days as defined by the World Meteorological Society in Switzerland, National Oceanic and Atmospheric Administration in the US, and China Meteorologic al Administration.
During a heatwave, older adults with functional decline face multiple challenges, he says. For instance, if an older person is bedridden and can’t dress themselves or move around easily, they might not be able to make efforts to stay cool or hydrated.
Cognitive impairments can also make weather forecasts ineffective, as the person involved may not understand or remember to take action to prevent undue exposure to heat. “These limitations significantly heighten their risk of heat-related illnesses such as heat exhaustion or heatstroke,” Ji says.
But older people who have someone looking out for them have a reduced risk, he adds.
“The key issue is not how sociable or the number of social interactions an older person has, but whether they have someone reliable to turn to during difficult times,” says Ji. “Our findings show that not having anyone to ask for help is the most significant risk factor — this is a key factor that is often overlooked.”
What can we do?
To combat this growing threat, Ji suggests a few key strategies.
Preserving functional abilities is essential, he says. Clinicians should integrate physical function assessments into routine checkups to identify those at heightened risk.
Expanding community services such as home visits and meal deliveries can also provide much-needed assistance, he says, helping seniors maintain their independence and functional abilities.
The Tsinghua University Vanke School of Public Health research team that studied the factors key to heatwave mortality risk in older adults was led by Associate Professor John S. Ji (pictured).
And using technology could be transformative, Ji argues, as devices could allow caregivers to monitor vital signs, automatically alerting them to health emergencies. Technology could also help direct older adults to places they can stay cool or activate air conditioning systems when temperatures reach certain levels, he says.
By integrating these strategies with a focus on healthy ageing practices, we can significantly reduce the risks faced by older adults during extreme heat events, says Ji. “Together, these tactics can really enhance resilience against the growing threat of extreme heat due to climate change,” he says.
Reference
Xi, D., Liu, L., Zhang, M. et al. Risk factors associated with heatwave mortality in Chinese adults over 65 years. Nat Med 30, 1489–1498 (2024). Doi: 10.1038/s41591-024-02880-4
Editor: Guo Lili
