Association of Social Frailty With Incident Dementia and Cognitive Decline in Middle-Aged and Older Adults: A Prospective Cohort Study.

IntroductionSocial frailty is a multidimensional construct encompassing social behaviors, social resources, and the fulfillment of basic social needs, and is increasingly recognized as an important factor influencing cognitive function. This study aimed to evaluate the association between social frailty and incident dementia as well as changes in cognitive function among middle-aged and older adults, providing novel evidence through a longitudinal cohort applying a multidimensional social frailty framework.MethodsData were derived from the China Health and Retirement Longitudinal Study (CHARLS). Social frailty was defined across four dimensions: general resources, social behavior, social resources, and basic social needs. Cognitive function was assessed using tests of memory, orientation, and executive function. Cox proportional hazards models were used to analyze the association between social frailty and incident dementia, and linear mixed-effects models were applied to examine the relationships between social frailty and changes in overall and domain-specific cognitive function.ResultsCompared with the socially robust group, the socially frail group showed an increased risk of incident dementia in Model 1 and Model 3 (HR = 2.42, 95% CI: 1.50-3.89, P < 0.001; HR = 1.52, 95% CI: 0.92-2.53, P = 0.102, respectively). Among the dimensions, only the social behavior dimension remained significantly positively associated with dementia risk (HR = 1.38, 95% CI: 1.11-1.73, P = 0.004). Regarding cognitive function changes, social frailty was significantly associated with decline in overall cognitive function (β = -0.12, 95% CI: -0.18 to -0.06, P < 0.001), primarily reflected in memory decline (β = -0.14, 95% CI: -0.21 to -0.08, P < 0.001), whereas no significant associations were observed for orientation or executive function.ConclusionSocial frailty is associated with a higher risk of incident dementia and faster cognitive decline, highlighting its potential as an early and modifiable risk marker for cognitive aging.