What does the GrimAge (Epigenetic Mortality Predictor Clock) test measure?

Why is GrimAge (Epigenetic Mortality Predictor Clock) measured?

GrimAge and GrimAge acceleration (GrimAge − chronological age) are the most powerful epigenetic predictors of all-cause mortality and lifespan currently available in the peer-reviewed literature, outperforming first- and second-generation clocks in prospective mortality prediction. In longevity and preventive medicine practice, elevated GrimAge acceleration is interpreted as a signal of biological mortality risk that exceeds what would be expected from chronological age alone, motivating aggressive lifestyle and medical intervention. Smoking history is a particularly strong driver of GrimAge acceleration — the clock was partially trained on smoking methylation signatures and reflects cumulative tobacco exposure with high sensitivity.

Reference ranges

Standard reference

Compared to chronological age — GrimAge is calibrated to predict time-to-death; acceleration above chronological age is the clinically significant finding. # REVIEWER FLAG: Confirm TruDiagnostic's GrimAge reporting format — raw age in years, delta from chronological age, or percentile. Confirm whether TruDiagnostic implements original GrimAge (Lu et al. 2019) or GrimAge2 (updated 2022 iteration).

Functional medicine optimal

GrimAge acceleration ≤ 0 (GrimAge ≤ chronological age); negative GrimAge acceleration is the longevity target. # REVIEWER FLAG: Optimal framing not standardised — reviewer to confirm.

Units

Years (biological age estimate)

Reference ranges vary by laboratory and assay platform. Interpret in context of the issuing laboratory's stated range.