Heatwave Exposure Accelerates Biological Aging via Metabolic Dysregulation

Heatwave (HW) exposure is increasing rapidly under climate change, yet its potential role in accelerating biological aging and the underlying mechanisms remain poorly understood. Leveraging data derived from the China Health and Retirement Longitudinal Study (CHARLS), a large population-based cohort in China, we examined whether exposure to HWs is linked to more rapid biological aging in adults of middle and advanced age. The Klemera-Doubal method (KDM) was applied to derive estimates of biological age (BA), and biological age acceleration (BAA) was calculated as biological age minus chronological age. HW exposure during the 12 months preceding BA assessments in 2011 and 2015 was quantified using 12 definitions based on different temperature threshold and duration. Longitudinal associations between HW exposure and BAA were evaluated using a difference-in-differences design. Among 2,318 participants (mean age, 58.7 years; 46.9% men), greater HW exposure was significantly associated with higher BAA. Under the most stringent (HW12; ≥4 consecutive days above the 97.5th percentile), each additional HW event and day increased BAA by 0.531 years [95% confidence interval (CI), 0.341 to 0.722] and 0.057 years (95% CI, 0.037 to 0.076). Stronger associations were observed among participants with body mass index ≥ 23 kg/m², urban residents, and those living in southern or subtropical regions. HW exposure was also additionally associated with higher levels of total cholesterol and glycated hemoglobin A1c (HbA1c) levels. To explore potential biological mechanisms, transcriptomic profiling was performed in aged mice exposed to HW conditions. HW exposure induced 29 differentially expressed genes enriched in lipid metabolism and insulin resistance pathways, providing biological plausibility for the observed epidemiological associations. These results suggest that recurrent HW exposure may contribute to accelerated biological aging, potentially through metabolic disruption, and highlighting the vulnerability of aging populations to climate-related thermal stress and the need for targeted climate-adaptation strategies.