This 2018 review explained:
“Aging is the sum of all age-related diseases. Aging and its diseases are inseparable, as these diseases are manifestations of aging.
An aged appearance (e.g., grey hair, wrinkles, cushingoid body types and loss of muscles) are manifestations of pre-diseases. For example, an aged appearance may reflect hypercortisolism, sarcopenia, osteoporosis, skin pre-diseases.
Instead of healthy aging, we could use the terms pre-disease aging or decelerated aging. Treatments are generally more effective at pre-disease stages, associated with hyper-function, than at disease stages, associated with functional decline.
The decision to treat or not to treat is often determined by whether it is possible to treat.
A treatment that slows aging increases both healthspan (subclinical period) and lifespan, whereas a treatment that increases lifespan (e.g., coronary bypass, defibrillation) is not necessarily increase healthspan. The goal of both anti-aging therapies and preventive medicine is to extend healthspan (by preventing diseases), thus extending total lifespan.
The fact that aging is an obligatory part of the life of all organisms is not important. Aging can be treated as a pre-disease to prevent its progression to diseases. Aging does not need to be defined as a disease to be treated.”
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6286826/ “Disease or not, aging is easily treatable”