Kaitlyn Lawrence, Ph.D.

Staff Scientist

National Institute of Environmental Health Sciences

Extreme heat events (defined as temperatures exceeding normal for a given region and season) have increased over the past few decades and pose a significant threat to human health and life. These events disproportionately affect racial and ethnic minority groups as well as people with low socioeconomic status, leading to disparities in heat-related morbidity and mortality.

Research suggests that epigenetic processes may play a role in the link between extreme heat events and adverse health outcomes. Recent applications of genome-wide DNA methylation include leveraging an individual’s methylome to determine elevated mortality risk, reduced lifespan, and increased age pacing using epigenetic clocks. Epigenetic clocks are a class of biological age predictors that use DNA methylation at predetermined cytosine-phosphate-guanine (CpG) sites to predict biological variation among those with the same chronologic age. Despite the promise of epigenetic clocks in identification of subgroups at risk for early mortality and disease, no studies have examined epigenetic aging related to extreme heat exposures.

To address this research gap, Dr. Lawrence’s study will:

1. Characterize the relationship between extreme heat events and epigenetic aging.
2. Evaluate the presence of sociodemographic disparities in this relationship.

Dr. Lawrence and research team will use data from the NIEHS Sister Study—a diverse U.S.-based prospective cohort of women designed to identify environmental risk factors for breast cancer and other diseases. The research team will leverage data from a subsample of women with peripheral blood-based methylation profiling obtained at a home examination. Three prominent epigenetic clock metrics, GrimAge, PhenoAge, and DunedinPACE, will be used to characterize epigenetic aging. Extreme heat events will be characterized using data from the PRISM database (Oregon State University, PRISM Climate Group), which comprises daily maximum temperatures from 1980–2022 at an 800-meter resolution. Extreme heat events will be linked to geocoded participant enrollment residential addresses.

Results from this study will provide insight into epigenetic-based changes associated with extreme heat exposure and will aid in the early identification of subgroups at high risk of adverse health outcomes from extreme heat exposures.