ABSTRACT
BACKGROUND: Indices of multimorbidity and deficit accumulation (ie, frailty indices) have been proposed as markers of biological aging. If true, changes in these indices over time should predict downstream changes in cognition and physical function, and mortality. METHODS: We examined associations that 8-year changes in (i) a multimorbidity index comprised of 9 chronic diseases and (ii) a frailty index (FI) based on deficit accumulation in functional, behavioral, and clinical characteristics had with subsequent measures of cognitive and physical function over 10 years. We drew data from 3 842 participants in the Action for Health in Diabetes clinical trial. They were aged 45-76 years at baseline and at risk for accelerated biological aging due to overweight/obesity and type 2 diabetes mellitus. RESULTS: A total of 1 501 (39%) of the cohort had 8-year increases of 1 among the 9 diseases tracked in the multimorbidity index and 868 (23%) had increases of ≥2. Those with greatest increases in multimorbidity tended to be older individuals, males, and non-Hispanic Whites. Greater FI increases tended to occur among individuals who were older, non-Hispanic White, heavier, and who had more baseline morbidities. Changes in multimorbidity and FI were moderately correlated (r = 0.26; p < .001). Increases in both multimorbidity and FI were associated with subsequently poorer composite cognitive function and 400-m walk speed and increased risk for death (all p < .001). CONCLUSIONS: Accelerated biological aging, as captured by multimorbidity and frailty indices, predicts subsequent reduced function and mortality. Whether intensive lifestyle interventions generally targeting multimorbidity and FI reduce risks for downstream outcomes remains to be seen. Clinical Trials Registration Number: NCT00017953.
