The root cause is damage. That is the mainstream view in the research community, for all that there is a lot of debate over which damage is actually fundamental

The root cause is damage. That is the mainstream view in the research community, for all that there is a lot of debate over which damage is actually fundamental and which damage is more important, or how the damage progresses in detail. Then there is secondary and later damage caused by systematic dysregulation resulting from the root cause damage. Then there is adaptation to damage, primary and secondary and later, which is some cases is beneficial and some cases not. E.g. epigenetic changes, stem cell quiescence, cardiovascular remodeling, etc. I'm vaguely optimistic about DNA methylation patterns as the basis for a biomarker precisely because they are not damage, but rather a reaction to that damage. In a way they are an evolved damage assessment, or at least they might be used in that way. We'll see how it pans out in practice over the next five years or so.