Repeated ageing clock readings predict mortality better
A single ageing clock measurement tells you relatively little. But track that same clock over time, and you suddenly have something far more useful: a direct read on how fast you are actually ageing.
Epigenetic clocks (tools that estimate biological age using patterns in DNA methylation) have been used for years in population studies. For individuals, however, their usefulness has been limited: single measurements vary considerably, and it is unclear what a deviation from chronological age actually means in practice.
The study, based on the Italian InCHIANTI cohort, shows that the change in clock scores over time is a stronger predictor of mortality than any single measurement. Individuals whose biological age advanced faster than average faced greater mortality risk in subsequent years. That may sound intuitive, but it had not previously been demonstrated with long-term follow-up data.
What does DNA methylation actually measure?
DNA methylation is a chemical modification of DNA that regulates gene activity without changing the underlying genetic code. As people age, methylation patterns shift in predictable ways. Algorithms that read those patterns are called epigenetic clocks. They estimate biological age, but also contain statistical noise.
By comparing measurements taken at two different time points, this approach partially filters out that noise. What remains is a measure of the rate of ageing for that specific individual. In the InCHIANTI study, that rate was significantly correlated with the probability of dying in the years that followed.
Implications for longevity research
This has practical consequences. When testing interventions such as drugs, lifestyle changes, or supplements, researchers want to know whether a treatment changes the pace of ageing. One measurement before and one after a treatment provides more information than a single snapshot alone. That makes repeated clock measurements a more attractive outcome measure for clinical trials.
The researchers emphasise this is not yet definitive proof that clocks are ready for clinical use. But it does lay a more solid foundation for that future application.
Want to research this yourself?
Search for example:
- DNA methylation biological age
- longitudinal epigenetic clock
- pace of ageing mortality risk