The association between sensory function changes, metabolic and inflammatory biomarkers, and cognitive impairment: two prospective cohort studies.

BACKGROUND: Recent findings indicate a correlation between sensory impairment and cognitive impairment, while earlier research primarily focused on baseline sensory function without addressing its progression. This research examines the association between dynamic changes in visual impairment (VI), hearing impairment (HI), and dual sensory impairment (DSI) with cognitive impairment, concurrently evaluating the mediating role of biomarkers.

METHODS: This research employed cohort data from the China Health and Retirement Longitudinal Study (CHARLS, 2011-2018) and the Health and Retirement Study (HRS, 2010-2018). Changes in sensory function were evaluated using initial and second follow-up datasets, with participants categorized into no SI, new-onset, remitted, and persistent. The quantification of cognitive impairment risk utilized multivariable-adjusted Cox proportional hazards regression models. Mendelian randomization (MR) was applied to infer genetic causality, while mediation analysis was performed to assess the influence of metabolic and inflammatory biomarkers.

RESULTS: This study analyzed data from CHARLS (N = 5224) and HRS (N = 8314), revealing that new-onset HI and DSI were significantly associated with an increased risk of cognitive impairment (CHARLS, HR 1.25-1.93; HRS, HR 1.05-1.67). Conversely, remitted HI or DSI was associated with a reduced risk (CHARLS, HR 0.62-0.95), particularly among individuals aged below 65. MR analyses confirmed a causal relationship between hearing loss and cognition, with high-density lipoprotein cholesterol and cystatin C demonstrating partial mediation effects.

CONCLUSIONS: Cognitive health strategies should incorporate regular screening and early intervention for sensory impairments (HI/DSI) among middle-aged and older populations.