Can an index of aging be constructed for evaluating treatments to retard aging rates? A 2,462-person study.

Biomarkers of aging are needed to evaluate proposed treatments to retard aging rates. At present, the only validated biomarker of aging is maximum life span, which remains impractical for human use. Identification of other biomarkers awaits development of a method of biomarker validation. This paper outlines an approach for this purpose intended for selecting biomarkers usable in humans. Prospective biomarkers are validated and weighted according to their correlation with interventions that, in healthy individuals, influence life span, namely mortality risk factors. A general mathematical method is presented for combining biomarker scores into an index of aging rate. This method addresses problems encountered with the traditional (multiple regression) method of calculating biological age and develops an index termed standardized biological age, SBA. In applying the method to 2,462 office workers, SBA, based on 12 physiological tests under investigation as biomarkers of aging, was found to depend on most of 17 surveyed dietary, exercise, life style, and geographical risk factors for mortality or health, suggesting that many risk factors predict rates of common functional declines with age. The 12 candidate biomarkers of aging in this study differed widely in validity according to the criterion employed. The approach holds promise for assembling an experimentally useful battery of biomarkers of aging.