The study tested whether sensory impairment predicts dementia beyond baseline cognition, in 51,584 UK Biobank participants aged 60-70. Vision and hearing were measured objectively, and participants were followed for incident dementia for a mean 12.1 years. After adjustment, direct-effect hazard ratios were 1.33 for visual impairment, 1.37 for hearing impairment and 2.21 for dual impairment. For dual impairment, the indirect effect through depressive symptoms, social isolation and cognition combined raised dementia risk by 10.5%. The design is observational and cognition rested on two brief tests, so the pathways show association, not cause.
Why it is interesting: Sensory loss is common in later life, and here it predicts dementia even after allowing for poorer starting cognition. Dual impairment more than doubles the risk, and isolation and low mood account for part of that effect.
Abstract — the authors' own words, CC BY
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 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.
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