Lexicon
Biological Age
Definition
Individuals with the same chronological age exhibit differential trajectories of age-related decline, so biological age should be assessed distinctly from chronological age. [1] Chronological-age estimators based on omics data and machine learning, known as aging clocks, provide a framework for interpreting molecular-level biological aging, because individuals of the same chronological age often exhibit divergent biological aging states resulting in distinct individual risk profiles. [2] Measuring biological age and the rate of aging at the molecular level is a prerequisite for efforts to target the aging process itself and extend healthspan. [3]
How it works
Epigenomic, transcriptomic, proteomic and metabolomic data can be harnessed with machine learning to build aging clocks that identify new biomarkers of biological aging. [3] The most widely used epigenetic clocks are based on DNA methylation patterns, with classic examples including Horvath's clock, Hannum's clock, DNA PhenoAge and DNA GrimAge. [4] Composite frameworks integrate molecular markers such as telomere length and epigenetic marks together with physiological function such as lung function to produce a score that measures biological aging in humans. [1]
Connected concepts
How it's measured
Epigenetic clocks comprise a set of CpG sites whose DNA methylation levels measure subject age and are acknowledged as a highly accurate molecular correlate of chronological age in humans and other vertebrates. [5] Beyond epigenetics, metabolomic aging clocks profile small molecules in the body and provide a readout of the genome-environment interaction, and microbiome-based clocks derived from gut and skin microbiota have also been proposed. [2] [6] Interpretation, cell-type heterogeneity and single-cell resolution remain open computational and statistical challenges that limit understanding and application of epigenetic clocks. [7]
What levels mean
When an epigenetic clock estimates an age higher than the chronological age the difference is termed epigenetic age acceleration, which numerous biological, social and environmental factors have been investigated for modifying.
Community knowledge
## Clocks And Measurement Science
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- 1.Khan SS, Singer BD, Vaughan DE. Molecular and physiological manifestations and measurement of aging in humans. Aging Cell · 2017
- 2.Huang H, Chen Y, Xu W, Cao L, Qian K, Bischof E, Kennedy BK, Pu J. Decoding aging clocks: New insights from metabolomics. Cell Metab · 2025
- 3.Rutledge J, Oh H, Wyss-Coray T. Measuring biological age using omics data. Nat Rev Genet · 2022
- 4.Duan R, Fu Q, Sun Y, Li Q. Epigenetic clock: A promising biomarker and practical tool in aging. Ageing Res Rev · 2022
- 5.Bell CG, Lowe R, Adams PD, Baccarelli AA, Beck S, Bell JT, Christensen BC, Gladyshev VN. DNA methylation aging clocks: challenges and recommendations. Genome Biol · 2019
- 6.Min M, Egli C, Sivamani RK. The Gut and Skin Microbiome and Its Association with Aging Clocks.
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