An increasingly diverse set of approaches are under development with the aim of measuring biological rather than chronological age. Assessing the age-related burden of damage and dysfunction with sufficient accuracy would enable cost-effective quantification of any potential rejuvenation therapy. It would hopefully steer the research community away from marginal treatments and towards more effective treatments in the near term. Unfortunately, despite a proliferation of such measures, it remains far from clear that any of them can be trusted once one starts in on treating aspects of aging. A given measure of aging may or may not be less sensitive or overly sensitive to the results of a therapy that only addresses one mechanism of aging, but there is no way to know in advance whether or not this is the case without extensive, lengthy calibration in animal and then human studies.
There is no single universal biomarker yet to estimate overall health status and longevity prospects. Moreover, a consensual approach to the very concept of aging and the means of its assessment are yet to be developed. Markers of aging could facilitate effective health control, more accurate life expectancy estimates, and improved health and quality of life. Clinicians routinely use several indicators that could be biomarkers of aging. Duly validated in a large cohort, models based on a combination of these markers could provide a highly accurate assessment of biological age and the pace of aging.
Biological aging is a complex characteristic of chronological age (usually), health-to-age concordance, and medically estimated life expectancy. This study is a review of the most promising techniques that could soon be used in routine clinical practice. Two main selection criteria were applied: a sufficient sample size and reliability based on validation. The selected biological age calculators were grouped according to the type of biomarker used: (1) standard clinical and laboratory markers; (2) molecular markers; and (3) epigenetic markers. The most accurate were the calculators, which factored in a variety of individual biomarkers. Despite their demonstrated effectiveness, most of them require further improvement and cannot yet be considered for use in standard clinical practice.