Exposure to ambient temperature and heat index in relation to DNA methylation age: A population-based study in Taiwan

Abstract

BackgroundClimate change caused an increase in ambient temperature in the past decades. Exposure to high ambient temperature could result in biological aging, but relevant studies in a warm environment were lacking. We aimed to study the exposure effects of ambient temperature and heat index (HI) in relation to age acceleration in Taiwan, a subtropical island in Asia. MethodsThe study included 2,084 participants from Taiwan Biobank. Daily temperature and relative humidity data were collected from weather monitoring stations. Individual residential exposure was estimated by ordinary kriging. Moving averages of ambient temperature and HI from 1 to 180 days prior to enrollment were calculated to estimate the exposure effects in multiple time periods. Age acceleration was defined as the difference between DNA methylation age and chronological age. DNA methylation age was calculated by the Horvath’s, Hannum’s, Weidner’s, ELOVL2, FHL2, phenotypic (Pheno), Skin & blood, and GrimAge2 (Grim2) DNA methylation age algorithms. Multivariable linear regression models, generalized additive models (GAMs), and distributed lag non-linear models (DLNMs) were conducted to estimate the effects of ambient temperature and HI exposures in relation to age acceleration. ResultsExposure to high ambient temperature and HI were associated with increased age acceleration, and the associations were stronger in prolonged exposure. The heat stress days with maximum HI in caution (80-90°F), extreme caution (90-103°F), danger (103-124°F), and extreme danger (>124°F) were also associated with increased age acceleration, especially in the extreme danger days. Each extreme danger day was associated with 571.38 (95 % CI: 42.63–1100.13), 528.02 (95 % CI: 36.16–1019.87), 43.9 (95 % CI: 0.28–87.52), 16.82 (95 % CI: 2.36–31.28) and 15.52 (95 % CI: 2.17–28.88) days increase in the Horvath’s, Hannum’s, Weidner’s, Pheno, and Skin & blood age acceleration, respectively. ConclusionHigh ambient temperature and HI may accelerate biological aging.