Aging does not erase all organs equally: in some it intensifies DNA methylation, in others it weakens it, and only a few changes are repeated almost everywhere.
This was shown by a large-scale study published in Nature Aging in 2026: a meta-analysis of over 15,000 DNA methylation profiles from 17 human tissues. Scientists from the Australian Institute for Regenerative Medicine collected data from 131 datasets and built the first detailed map of age-related epigenetic changes.
Each organ accumulates its own "imprint" - in skeletal muscle, adipose tissue, liver, brain, and lungs, methylation patterns diverge. At the same time, several co-methylation modules were common to most tissues. Among the enriched pathways, researchers highlighted processes associated with NAD+ metabolism - a key cofactor of cellular energy and DNA repair.
The strength of the work lies in its volume and cross-tissue approach: the data covers the adult lifespan and allows for direct comparison of tissues. The weakness is the correlational nature: methylation reflects age but does not prove that these specific changes cause functional decline. There are no clinical trials of interventions in the NAD+ pathway based on this map yet.
Imagine a library where each room is a separate organ. Time doesn't just yellow all the pages the same way: in the reading room, books lose their table of contents, in the archive, their spines are re-glued, and in the rare book storage, pages stick together. And yet, in every room, the same marginal note appears - a trace indicating a common wear mechanism.
A public data atlas is already available, allowing other groups to test hypotheses without new large samples. The question now is not whether the body ages as a whole, but how accurately the "age" of a specific organ can be measured and whether common molecular nodes can be intervened in before the differences become irreversible.
