Climate-related disasters and biological aging based on DNA methylation: a twin and family study in Australian women

BACKGROUND: Weather-related disasters are devastating and may exhibit greater intensity globally under a changing climate, leaving survivors with greater and sustained health risks. However, the potential epigenetic mechanisms underlying the persistent adverse health impacts remain unclear. We aimed to examine the association between tropical cyclones (TCs) or flood exposure and biological aging based on DNA methylation. METHODS: We analysed peripheral blood samples from 479 women in 130 families across Australia and derived six metrics of DNA methylation age acceleration (DNAmAgeAC) for each participant, including Horvath's, Hannum's, and Zhang's DNAmAge, PhenoAge, and GrimAge versions 1 (GrimAge1) and 2 (GrimAge2). Linear mixed-effect and distributed lag nonlinear models accounting for familial clustering and delayed effects were used to estimate the DNAmAgeAC associated with TCs or flood exposure. RESULTS: TCs or flood exposures were generally associated with higher DNAmAgeAC of various metrics, which persisted for ≤6 months after exposure. Overall, participants exposed to TCs or floods had higher DNAmAgeAC based on Horvath's age [2.66 years, 95% confidence interval (CI): -2.94 to 8.27; P = .357], Hannum's age (6.81 years, 95% CI: 1.75-11.88; P = .008), PhenoAge (8.96 years, 95% CI: 2.35-15.57; P = .008), Zhang's age (0.93 years, 95% CI: -0.56 to 2.42; P = .224), GrimAge1 (2.60 years, 95% CI: -0.64 to 5.83; P = .115), and GrimAge2 (4.31 years, 95% CI: 0.52-8.09; P = .026). Socioeconomic status, age, smoking, and drinking behaviors modified the associations, with generally stronger adverse associations observed among the participants living in lower socioeconomic areas, <60 years of age, with higher smoking indices, or being current/former drinkers. The adverse associations were partially mediated by a shift in leucocyte distributions, particularly the change in the proportions of naive CD8+ T cells, exhausted cytotoxic CD8+ T cells, and granulocytes. CONCLUSION: TC or flood exposures were associated with accelerated biological aging measured by using DNA methylation in Australian women, especially for those living in lower socioeconomic areas, <60 years of age, who were more smokers or drinkers. The accelerated aging may be partially contributed by the potential infections and alterations in the immune status in human bodies after climate-related disasters.