A comprehensive evaluation on the associations between hearing and vision impairments and risk of all-cause and cause-specific dementia: results from cohort study, meta-analysis and Mendelian randomization study

Abstract

Background: Epidemiological studies show inconsistent links between hearing/vision impairment and dementia risk. Using multisource data, we investigated how single or combined sensory impairments relate to risks of all-cause and specific types of dementia. Methods: We employed a triangulation approach combining three methodologies. We analyzed 90,893 UK Biobank (UKB) adults to explore single and joint effects of hearing and vision impairments on all-cause and Alzheimer’s disease (AD), vascular dementia (VD) and non-AD non-VD (NAVD). A meta-analysis of prospective studies involving 937,908 participants provided stronger evidence. Finally, we conducted Mendelian randomization (MR) analysis using genome-wide association studies from UKB (361,194 participants) and FinnGen (412,181 participants) to validate relationships between sensory impairments and dementia occurrence. Results: In the UKB cohort study, compared to participants with normal hearing, those in the mild and severe hearing impairment groups had progressively and significantly higher risk of all-cause dementia (mild: HR1.52, 95%CI 1.31–1.77; severe: HR1.80, 95%CI 1.36–2.38), AD (mild: HR1.63, 95%CI 1.30–2.04; severe: HR2.18, 95%CI 1.45–3.27), VD (mild: HR1.68, 95%CI 1.19–2.37; severe: HR1.47, 95%CI 1.22–1.78), and NAVD (mild: HR1.47, 95%CI 1.22–1.78; severe: HR1.98, 95%CI 1.43–2.75). Besides, vision impairment was associated with an increased risk of all-cause dementia (HR1.55, 95%CI 1.18–2.04) and NAVD (HR1.51, 95%CI 1.07–2.13). Furthermore, dual sensory impairment was associated with stepwise increased risks of all-cause and cause-specific dementia than single hearing or vision impairment. In the meta-analysis of 31 prospective cohort studies, risks of all-cause dementia and AD were elevated in participants with single hearing impairment (all-cause dementia: HR1.30, 95%CI 1.21–1.40; AD: HR1.30, 95%CI 1.21–1.40) and dual sensory impairment (all-cause dementia: HR1.63, 95%CI1.14–2.12; AD: HR 2.55, 95%CI 1.19–3.91), while single vision impairment only associated with higher risk of all-cause dementia (HR1.43, 95%CI 1.16–1.71) but not AD. Finally, the MR analysis revealed a significant association between hearing impairment and all-cause dementia (OR1.74, 95%CI 1.01–2.99), AD (OR1.56, 95%CI 1.09–2.23), and NAVD (OR1.14, 1.02–1.26), as well as vision impairment and NAVD (OR1.62, 95%CI 1.13–2.33). Conclusions: Our findings showed significant associations between hearing and vision impairments and increased risks of all-cause and cause-specific dementia. Standardized hearing and vision assessment and intervention should be emphasized in dementia prevention strategies.