Effects of ambient temperature on hospital admissions and mortality among older adults with and without dementia in South Korea.

Background: Dementia is a growing health problem as the global population ages. However, the research on the effects of ambient temperatures on various health outcomes among people with dementia remains limited. This study examined the association between daily temperatures and hospital admissions for dementia among older adults with dementia, as well as their association with all-cause hospital admissions and mortality among individuals with and without dementia.

Methods: This study utilized the National Health Insurance Service-Senior Cohort from 2002 to 2019, consisting of approximately one million older adults in South Korea. Individuals with dementia were identified based on medical claims. Daily mean temperatures were obtained from national monitoring stations and averaged at the province level. We employed a time-stratified case-crossover design to estimate the association between daily temperatures and the risk of hospital admissions and mortality.

Results: In the total cohort of 1 057 784 individuals, 78 424 were identified as having dementia. The association between temperature and dementia admissions showed a hockey stick-shaped curve, indicating an elevated risk at higher temperatures. The relative risk (RR) for dementia admissions at the 99th percentile temperature compared to the 50th percentile temperature was 1.36 (95% confidence interval: 1.19-1.57). Individuals with dementia showed more pronounced increases in all-cause hospital admissions and mortality at high temperatures compared to those without dementia.

Conclusions: Our study found that high temperatures increased the risk of hospital admissions for dementia in older adults with dementia. Additionally, those with dementia may experience greater health impacts from extreme temperatures than those without, due to physiological and behavioral vulnerabilities.