In this paper the author looks ar the oucomes of past efforts to modestly extend life, mostly in the laboratory only, via the traditional drug discovery and development process, or pharmacology. I'd argue that any debate over targeting lifespan versus healthspan is an artifact of focusing on strategies that can do very little in the grand scheme of things, either slightly slowing aging or slightly compensating for one or more aspects of aging without addressing its causes. Only in this realm is it possible to produce therapies that could extend life without extending health to match. It becomes moot for true rejuvenation therapies that repair the underlying cell and tissue damage that causes aging, and are capable in principle of extending life by decades if made effective enough at that repair. At that scale of life extension, and by that methodology of damage repair, healthspan and lifespan are extended in tandem - it isn't possibly to move one independently of the other. Present damage determines both current health and future trajectory of health and mortality absent future repair.
The main goal of this paper is to present the case for shifting the focus of research on aging and anti-aging from lifespan pharmacology to what I like to call healthspan pharmacology, in which the desired outcome is the extension of healthy years of life rather than lifespan alone. Lifespan could be influenced by both genetic and epigenetic factors but a long lifespan may not be a good indicator of an optimal healthspan. Without improving healthspan, prolonging longevity would have enormous negative socioeconomic outcomes for humans. The goal of aging and anti-aging research should therefore be to add healthy years to life and not to merely increase the chronological age.
This paper summarizes and compares two categories of pharmacologically induced lifespan extension studies in animal model systems from the last two decades: those reporting the effects of pharmacological interventions on lifespan extension alone, versus others that include their effects on both lifespan and healthspan in the analysis. The conclusion is that the extrapolation of pharmacological results from animal studies to humans is likely to be more relevant when both lifespan and healthspan extension properties of the pharmacological intervention are taken into account.