Cognitive Function Modifies the Association Between Heatwave Exposure and Cardiovascular Disease Risk in Older Adults: Evidence From The CHARLS

Background Cardiovascular disease (CVD) is a leading cause of death and disability worldwide, and its burden is rapidly increasing among China’s aging population. Evidence links heatwaves to CVD outcomes. However, the impact of non-summer nighttime heatwaves and the modifying role of cognitive function in older adults remain unclear. Methods We used data from Wave 4 (2018) and Wave 5 (2020) of the China Health and Retirement Longitudinal Study to construct a cohort of 5,566 participants aged ≥ 60 years without CVD at baseline. Non-summer nighttime heatwaves were defined using city-specific percentiles of daily minimum temperature (90th-97.5th) combined with durations of ≥ 2–4 consecutive days, and exposure was measured as the change in heatwave days or events over two years. Cognition were assessed using the Mini-Mental State Examination, with education-adjusted cut-offs defining impairment. Difference-in-difference generalized additive models with a logit link was used to estimate odds ratios and 95% confidence intervals for CVD incidence, and to test for interaction by cognitive function. Results During follow-up, 510 participants (9.16%) developed incident CVD. Higher non-summer nighttime heatwave exposure was associated with increased CVD risk, and longer heatwave duration under the same thresholds represented to greater risk. Associations were stronger among participants with cognitive impairment, and deficits in orientation or executive function particularly amplified CVD risk under non-summer nighttime heatwaves. Conclusions Non-summer nighttime heatwaves are associated with elevated incident CVD risk in mid-Age and Elderly in China, especially among those with cognition impairment. Integrating targeted heat-health protection for cognitively impaired older adults into CVD prevention strategies may help reduce the cardiovascular harms of climate change.