Visual, hearing, and dual sensory impairment and risk of dementia: The role of social isolation, depressive symptoms, and cognitive function

Objective Sensory impairment (SI), including visual impairment (VI), hearing impairment (HI), and dual sensory impairment (DSI), is common in aging adults and associated with increased dementia risk. Older adults with SI often have poorer cognition, a predictor of dementia. We investigated associations of VI, HI, and DSI with incident dementia while accounting for baseline cognition, and assessed indirect pathways through cognition, social isolation, and depressive symptoms. Methods 51,584 UK biobank participants aged 60–70 years with objectively measured visual and hearing function were followed for incident dementia for a mean of 12.1 years. VI was defined as visual acuity worse than 0.30 LogMAR in better-seeing eye; HI as speech-reception threshold in noise greater than −5.5 dB; DSI as both VI and HI. Cognition was assessed using pairs matching and reaction time tests. Dementia was ascertained through linked medical records and death registries Results After adjustment for cognition and covariates, VI, HI, and DSI remained associated with increased incident dementia risk. Direct-effect HRs were 1.33 for VI, 1.37 for HI, and 2.21 for DSI (all p < 0.05). VI, HI and DSI were also indirectly associated with dementia through depressive symptoms, social isolation, and cognition. The total indirect effect of DSI through all mediators increased dementia risk by 10.5%. Conclusions VI, HI, and DSI were associated with dementia risk through direct and indirect pathways. Findings support prevention and treatment of VI and HI as potentially modifiable dementia risk factors, and highlight integrated sensory, cognitive, and psychosocial approaches for dementia prevention and healthy aging.