Carrie Nielson is an epidemiologist focused on genetic risk factors for osteoporosis and other outcomes of aging that are related to body composition and endocrinology. She and her colleagues work to understand the regulation of bone, fat, and lean mass in older adults in order to prevent frailty and fracture, which lead to immobility and loss of independence. She works primarily on two large cohort studies of aging men and women in the United States, using genotyping in these cohorts to explore genetic variants that may affect bone mineral density and other traits.