Multisystem aging discordance and cognitive decline in Chinese older adults: A longitudinal study from CHARLS

Background Multisystem aging discordance may represent an early risk factor for cognitive decline, but prospective evidence in Chinese older adults is limited. Objective We constructed a blood-based Aging Discordance Index (ADI) and examined its 3-year association with cognitive function in a nationally representative Chinese cohort. ADI was derived from five routine biomarkers (creatinine, total cholesterol, C-reactive protein, mean corpuscular volume, and glycated hemoglobin). Methods Data were from the China Health and Retirement Longitudinal Study (CHARLS). ADI was calculated as the standard deviation of age-adjusted Z-scores. Cognitive function was assessed via orientation, calculation, drawing, and equated word recall in 2018 data. Survey-weighted linear regression adjusted for baseline cognition, sociodemographic, lifestyle, and clinical covariates. Results Among 1688 participants aged ≥60 years, higher ADI was independently associated with worse 3-year cognitive performance (fully adjusted β = -0.336, 95% CI: −0.598 to −0.075, p = 0.011) and greater cognitive decline (β = -0.326, 95% CI: −0.575 to −0.077, p = 0.010). To address potential bias due to loss to follow-up, we further applied linear mixed models (LMM) with random intercepts in an expanded sample of 2912 participants, which utilizes all available repeated measures. The ADI × time interaction remained significant (β = –0.346, 95% CI: −0.580 to −0.112, p = 0.004), confirming the robustness of the primary findings against attrition bias. Conclusions A simple blood-based index of multisystem aging discordance independently predicts cognitive decline in Chinese older adults. ADI may offer a practical, low-cost tool for early risk stratification in community settings.