Examining Social Isolation as a Mediator of the Association Between Hearing Impairment and Dementia: Evidence From the National Health and Aging Trends Study

Objectives Previous studies link hearing impairment to greater social isolation and show they both independently increase dementia risk among older adults. Yet, it remains unclear whether social isolation mediates the relationship between hearing impairment and dementia. This study examines the roles of social isolation as a confounder or a mediator on the longitudinal association between hearing impairment and dementia Measurement Using longitudinal data from 2011-2022 National Health and Aging Trends Study, we estimated risk of dementia associated with hearing impairment using Cox-proportional hazard models after separately adjusting for demographic, socioeconomic, health status characteristics and social isolation. In addition, we employed the four-way decomposition method with parametric regression models to estimate the mediation effects of social isolation on the association of hearing impairment and dementia. Result Hearing impairment was associated with a greater than 2-fold increased dementia risk after adjusting for social isolation and other factors. Approximately 5 percent of this risk was positively mediated by social isolation. Conclusion Our results suggest that social isolation acts as a limited mediator to the associations of hearing impairment and dementia risk. This suggests that reduced social engagement partially explains, but does not drive, the hearing–dementia link. Interventions addressing both hearing loss and social isolation may jointly help reduce dementia risk in older adults.