Association of frailty with cognitive functioning in older adults: The Chain-mediated effects of sleep and mood regulation and the moderating role of activities of daily living

BACKGROUND AND AIM: Population aging exacerbates the public health challenge of cognitive impairment, and frailty, a prominent health problem in the older population, is closely associated with cognitive decline. The aim of this study was to investigate the mechanisms by which frailty affects cognitive functioning in older adults, and to test the chain-mediated effects of sleep quality and depression, as well as the moderating effects of activities of daily living (ADL). METHODS: 1645 older adults from 10 communities in Jiangsu Province, China, were surveyed from May to December 2024 using a cross-sectional design. Cognitive function, frailty, sleep quality, depression, and ADL were assessed by the Montreal Cognitive Assessment, FRAIL scale, Pittsburgh Sleep Quality Index, Patient Health Questionnaire, and ADL Scale.Mediating and moderating effects were analyzed using stratified regression modeling and Bootstrap method. RESULTS: Frailty significantly negatively predicted cognitive function (β = -0.278, P < 0.001). Sleep quality (β = -0.129, 95%CI [-0.184, -0.085]) and depression (β = -0.0316, 95%CI [-0.060, -0.005]) partially mediated the association between frailty and cognitive function, and there was a chained mediation effect between the two (β = -0.003, 95%CI [-0.006, -0.0003]). ADL significantly moderated the effect of frailty on cognitive function (interaction term β = 0.036, P = 0.0004), but its moderating effect on the mediating pathway was not significant. CONCLUSIONS: Frailty indirectly impairs cognitive functioning through decreased sleep quality and depressive symptoms, and ADL mitigates the negative effects of frailty. Future interventions need to focus on frailty management, sleep improvement and psychological support, and encourage older adults to participate in daily activities to slow cognitive decline.