Assessment of multidimensional measures of aging cross-sectionally and longitudinally across the entire adult age span in the United Kingdom.

Background Aging is a complex process, starting early in life, manifesting across a hierarchy of biological bodily domains with heterogeneity by sex and increasing age. Several molecular and organ-level biological aging measurements have been developed. Reported associations of these measurements with aging-related functional health status are typically limited to cross-sectional research and studies in old people only. Methods Using data from UK Household Longitudinal Study, we examined associations between composite biological aging measures (Biological Health Score and DNA methylation algorithms) and grip strength, cognitive function, Short Form 12-item Survey scores, self-rated health cross-sectionally (up to 13 231 participants), as well as subsequent 12-year trajectories of Short Form 12-item Survey scores and self-rated health (up to 112 915 observations). Results Accelerated biological aging was found to be associated with worse functioning both cross-sectionally and longitudinally. However, associations can be moderated by sex and age group. For example, longitudinally, Biological Health Score was negatively associated with self-rated health (coefficient = -0.06) with a moderating effect of sex (coefficient = -0.02, p < .05; male = reference) and some age groups (40-52 years: coefficient = -0.04, p < .001; 53-65 years: coefficient = -0.03, p < .01; reference = 16-39 years), but not for the oldest group (66+ years: coefficient = -0.01, p = .34). Conclusions We conclude that measures of biological age are associated with individual functioning trajectories across the entire adult age span, and studies should consider sex differences and examine the entire age range to fully capture distinct facets of aging complexity.