SystemsAge

SystemsAge is a multi-organ biological-age framework introduced by Tian and colleagues (2023, Nature Medicine) that uses routine clinical laboratory data to generate organ-specific age estimates across 3 brain systems (cerebral cortex, thalamus, cerebellum) and 7 body systems (cardiovascular, respiratory, renal, gastrointestinal, liver, musculoskeletal, immune) — 10 systems total — from blood-based biomarker panels. Rather than a single composite score, it produces a profile of organ biological ages, allowing detection of discordant ageing across systems. In the UK Biobank, organ age gaps predicted organ-specific disease and all-cause mortality; individuals whose organ ages were globally younger than their chronological age showed lower mortality risk. The approach is attractive for scalable population studies because it relies on standard blood tests rather than DNA methylation arrays or imaging. A separate methylation-based 'SystemsAge' clock by Sehgal et al. 2025 Nature Aging (Levine lab) covers 11 physiological systems via a single blood-based assay; the two clocks share a name but use different inputs.