Aging clocks respond differently to the same treatment

The tools in question are epigenetic clocks (DNA methylation biomarkers): molecular instruments that track how chemical tags on DNA shift with age. They are intended as a measure of biological aging. But do they work as a gauge for whether a treatment is having an effect? The researchers analysed 51 existing longitudinal studies and tested 16 epigenetic clocks alongside 94 other DNA methylation markers.

Pharmacological interventions produce the strongest signals

The results show that different clocks respond very differently to the same intervention. Pharmacological treatments (including metformin, rapamycin, semaglutide and anti-TNF therapy) produced the strongest and most consistent signals in the biomarkers. Lifestyle interventions such as diet and exercise gave weaker, less consistent signals.

The researchers distinguish between two types of biomarkers. First, surrogate markers, intended to predict long-term outcomes. Second, discovery markers, which help explain which molecular mechanism an intervention affects. Both types are useful, but for different purposes.

Not yet a validated endpoint for clinical trials

The study makes one thing clear: the clocks are not yet sufficiently validated to serve as formal endpoints in clinical trials. That matters for the entire longevity sector, which increasingly relies on these biomarkers to speed up results. Rather than waiting decades for hard outcomes (such as disease or death), researchers hope to determine within years whether a therapy works.

Lead author Raghav Sehgal puts it this way: if these biomarkers are eventually validated as reliable indicators of long-term health, it should be possible to see within months which interventions are effective and in whom. That remains a prospect rather than a reality, but the systematic comparison this study provides is a step in that direction.

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