The research community is engaged in a the search for a reliable, agreed upon way to measure biological age, the burden of cell and tissue damage that causes dysfunction, disease, and death. Given such a reliable, cost-effective measure, potential rejuvenation therapies could be much more rapidly discovered, validated, and optimized than is presently the case. Researchers here review the present state of the art in this part of the field, and the challenges faced in trying to measure - or even rigorously define - biological age.
Putting together a conclusive theory of aging has been difficult due to the inability to properly quantify and define aging. Consequently, the efficacy of various geroprotective interventions remains subject to controversy. Without general agreement as to what constitutes aging and biological age (BA), and how to measure their progression, conclusions on the benefits of particular therapies are likely to be biased. Meanwhile, the very existence of a reliable way to measure BA remains under question.
It is possible that aging has no distinct genetic signature and is in essence a multitude of simultaneous damage accumulation processes. If that is true, BA as a concept is unlikely to be a property of objective reality but should be treated as an artificial construct. If there is indeed no singular process behind all the manifestations of aging, measuring BA is infinitely harder than in the case of single-source aging. It would require either (a) finding a common denominator for the majority of aging-related processes or (b) arbitrarily weighing all such processes according to their perceived importance to form the final "age score".
The problem of multiple aging processes is further confounded by individual variability. There are indications that people age according to different trends that can be grouped into several "ageotypes" defined by the hierarchical clustering of their biomarkers. Moreover, the fluidity of individual ageotypes can cause unstable performance of an aging score within any singular individual. Nonetheless, a reliable and universally agreed upon way to quantify BA is a necessity for modern biogerontology. Most importantly, it would enable flexible experimental designs and in many cases would remove the need to follow up human subjects for decades to evaluate the benefits of a geroprotective intervention. Moreover, it could be used as a criterion to test the relevance of specific diseases, pathways or processes in the context of aging research.
Link: https://doi.org/10.1...arr.2020.101050
View the full article at FightAging
