Weekend Healthcare Pulse: Age may be just a number... but could "biological age" be a different number entirely?

This weekend pulse examines the science behind "biological age" tests, the companies commercializing them, and the expanding set of biomarkers being recruited. Much of the field rests on DNA methylation: Steve Horvath's 2013 work showed methylation patterns predict age with remarkable accuracy, and his clock uses 353 CpG sites trained across more than 30 tissues and cell types. Departures from chronological age — epigenetic age acceleration — have been linked to frailty, cognitive decline, cardiovascular disease, some cancers and mortality risk. Consumer offerings diverge sharply: TruDiagnostic reports multiple clocks including GrimAge and DunedinPACE across 17 pages of data for biohackers and longevity physicians; Tally Health, founded by Harvard geneticist David Sinclair, simplifies the experience around a single TallyAge score plus a self-reported lifestyle quiz;