Telomere, epigenetic clock, and biomarker-composite quantifications of biological aging: Do they measure the same thing?

The geroscience hypothesis posits that therapies to retard biological processes of aging can prevent disease. To test such \"geroprotective\" therapies in humans, surrogate endpoints are needed for extension of disease-free lifespan. Methods to quantify biological aging could provide such surrogate endpoints, but different methods have not been systematically evaluated in the same humans. We studied seven measures of biological aging in 964 middle-aged humans in the Dunedin Study: telomere-length, three epigenetic-clocks, and three biomarker-composites. Agreement between these different measures of biological aging was low. We also compared associations between biological aging measures and