Sensory impairment, loneliness, and the discordance between subjective and objective cognitive function among older adults: a multi-cohort study

Objectives This study aimed to examine the association between sensory impairment and the discordance between subjective/objective cognitive function among older adults and test the mediating effect of loneliness. Methods We used data from four cohort studies conducted in 16 countries (N=19,119). Sensory impairment and subjective cognitive impairment were self-reported. Objective cognitive impairment was measured in three dimensions. Generalized estimating equations were conducted to examine the association between sensory impairment and discordance in subjective/objective cognitive function. Cross-lagged panel model and a bootstrap method with 2,000 samples were employed to verify the mediating effect. Results Sensory impairment was related to an increased risk of subjective cognitive impairment (OR=4.70, 95% CI 4.33-5.10), objective impairment (OR=1.51, 95%CI 1.31-1.74), as well as the discordance in subjective/objective cognitive function (OR=1.35, 95%CI 1.06-1.71 for older adults with normal subjective cognitive function). In contrast, sensory impairment was associated with a decreased risk of discordant subjective/objective cognitive function among those with subjective cognitive impairment (OR=0.79, 95%CI 0.66-0.94). Moreover, loneliness mediated the association between sensory impairment and subjective cognitive impairment (standardized indirect effect=0.002, 95%CI 0.001-0.004), objective cognitive impairment (standardized indirect effect=0.005, 95%CI 0.003-0.007) as well as the discordance in subjective/objective cognitive function (standardized indirect effect=0.001, 95%CI 0.001-0.003 for older adults with normal subjective cognitive function). Conclusions Significant association between sensory impairment and discordance in subjective/objective cognitive function and the mediating role of loneliness were revealed, varying by subjective cognitive function. Early screening on sensory impairment and targeted interventions on loneliness should be considered in future policies on cognitive impairment.