Since around the time at which the goal of extending life through improvements in medical technology became a respectable goal, let us say somewhere a little after 2010, perhaps around the time that the first demonstration of clearing senescent cells in mice was conducted, the official message from the academic research community to the public and politicians has been that the goal of the field is to extend healthspan, but not lifespan. Extending the healthy period of life is great, but extending overall lifespan is shady and disavowed. Why did the prominent figures of aging research so enthusiastically embrace this public messaging?
Today's open access paper provides one view on that question, but I don't think that it touches closely enough on what seems the actual answer. It seems quite clear to those of us who lived through that period of time that this messaging was a way to distance the dominant factions in academia, who are ever sensitive to any threat that might impact their perceived status and thus ability to raise funds, from the growing voices of patient advocates and a minority faction of researchers who had started to achieve some success in talking up radical life extension and the medical control of aging, while funding research into technologies to repair cell and tissue damage thought to cause aging. The "healthspan but not lifespan" messaging was a rush to conservatism undertaken in fear of reduced funding from conservative institutions. This is, after all, what happened in the field of aging research following the anti-aging advocacy and birth of the supplement industry in the 1970s. The leaders of the field disavowed any attempt to intervene in aging. It was an exclusion of those not following the orthodoxy, and a rebranding and message intended to distinguish the orthodox form the newcomers, all conducted to protect existing status and sources of funding.
But make your own mind up! One could also argue, much as is done in the paper here, that it was a reaction to the data obtained from decades of efforts to treat age-related diseases. Since those efforts did not in fact target causes of aging, they produced very little gain in life span, but heroic efforts in development and clinical practice had managed to incrementally extend healthspan. It takes enormous effort to coax a failing machine into continued function if repair is off the table, but it can be achieved to some degree. Still, some researchers may have felt that this outcome represented the bounds of the possible, and thus the newcomers who aimed to extend life span by changing the strategy to medicine to one of repairing causative damage were mistaken.
Against "Extending Healthspan but Not Lifespan" as a Goal for Biogerontology
Extending human healthspan is of course highly desirable. However, within the biogerontology field one increasingly encounters this view that our goal should be to extend healthspan but not lifespan. This view has been stated explicitly, for example by Jay Olshansky, who argued that "life extension should no longer be the primary goal of medicine when applied to people older than 65 years of age. The principal outcome and most important metric of success should be the extension of healthspan." From some perspectives, this is a strange position to take. What is wrong with extending lifespan? We suggest that this anomaly has arisen from conflation of the goals of two distinct disciplines, namely geriatric medicine, that addresses the health needs of older adults, and biogerontology, the study of the biology of aging.
A challenge for geriatricians is that all of their patients will inevitably die from the condition that ails them, namely the process of senescence (aging). Faced with this, laudable and inspiring goals for geriatric medicine were set out in the early 1980s in a vision that accepts the harsh fact that, as in most animal species, there exists an upper ceiling for human longevity. Thanks to improvements in public health during the last century or so, an increasing proportion of the population are living longer lives, coming closer to the longevity ceiling. This is reflected in an increasing rectangularization of population survival curves. It was argued that the goal of late-life medicine should be to reduce the proportion of later life in poor health: "The rectangularization of the survival curve may be followed by rectangularization of the morbidity curve and by compression of morbidity."
By contrast, the vision of biogerontology is very different. Central to it is the possibility of decelerating or even reversing the aging process as a whole, or in its greater part. That this is feasible is suggested by the existence of numerous interventions that extend both healthspan and lifespan in animal models, particularly rodents. In terms of medical applications, the main, ultimate goal of biogerontologists is much the same as that of most of medical research: to alleviate illness, reduce disease burden, and save lives. Anti-aging treatments will always reduce disease, and may extend lifespan, but whether they increase healthspan and compress morbidity is to a large extent a matter of chance. For a biogerontologist to say that their goal is to increase healthspan but not lifespan is as strange as for a practitioner of any other medical specialism (say, oncology) to say it.
The arguments for healthspan rather than lifespan originated in the field of geriatrics, in which they are cogent, but were subsequently imported into biogerontology, where they are not. Possibly this partly reflects efforts by biogerontologists to align themselves with the agenda of the broader and better funded biomedical field, particularly as part of the geroscience agenda. In the end, medical interventions that save lives and postpone death may or may not cause an expansion of morbidity. Whether they do or not, such interventions are beneficial to the patient, and a good thing. The prospect of a doctor denying a patient a life-saving treatment on grounds that they will remain alive for an extended period in poor health is not part of any ethical reality. We advocate that biogerontologists frankly state their goals of understanding and intervening in aging, to make any gains possible in terms of improvements to late-life health and saving of lives (i.e. life extension).
View the full article at FightAging
