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.
Level 3 - non-randomized controlled study
Triangulation study combining prospective cohort analysis, meta-analysis of prospective cohort studies, and Mendelian randomization
PubMed 39506811 · doi:10.1186/s12916-024-03748-7
What was done
The authors used a triangulation design combining three methodologies to examine single and combined hearing and vision impairments and risks of all-cause dementia, Alzheimer's disease (AD), vascular dementia (VD), and non-AD non-VD (NAVD): 1. A prospective cohort analysis of 90,893 adults in the UK Biobank. 2. A meta-analysis of 31 prospective cohort studies including 937,908 participants. 3. A Mendelian randomization (MR) study utilizing genome-wide association data from the UK Biobank (n = 361,194) and FinnGen (n = 412,181).
What was found
- UK Biobank cohort: Mild hearing impairment increased risk of all-cause dementia (HR 1.52, 95% CI 1.31–1.77), AD (HR 1.63, 95% CI 1.30–2.04), VD (HR 1.68, 95% CI 1.19–2.37), and NAVD (HR 1.47, 95% CI 1.22–1.78). Severe hearing impairment further elevated risks: all-cause dementia (HR 1.80, 95% CI 1.36–2.38), AD (HR 2.18, 95% CI 1.45–3.27), VD (HR 1.47, 95% CI 1.22–1.78), and NAVD (HR 1.98, 95% CI 1.43–2.75). Vision impairment was associated with all-cause dementia (HR 1.55, 95% CI 1.18–2.04) and NAVD (HR 1.51, 95% CI 1.07–2.13). Dual sensory impairment showed stepwise increased risk compared to single impairment. - Meta-analysis: Single hearing impairment was associated with all-cause dementia (HR 1.30, 95% CI 1.21–1.40) and AD (HR 1.30, 95% CI 1.21–1.40). Dual sensory impairment carried higher risk (all-cause dementia HR 1.63, 95% CI 1.14–2.12; AD HR 2.55, 95% CI 1.19–3.91). Vision impairment was associated with all-cause dementia (HR 1.43, 95% CI 1.16–1.71) but not AD. - Mendelian randomization: Genetically predicted hearing impairment was associated with all-cause dementia (OR 1.74, 95% CI 1.01–2.99), AD (OR 1.56, 95% CI 1.09–2.23), and NAVD (OR 1.14, 95% CI 1.02–1.26). Vision impairment was associated with NAVD (OR 1.62, 95% CI 1.13–2.33).
Why it matters
By combining individual cohort data, systematic meta-analysis, and genetic Mendelian randomization, this study provides multi-layered evidence that sensory deficits—especially hearing and dual sensory loss—are robust risk factors for dementia and its subtypes, reinforcing sensory screening as a key public health priority.
Limits
The abstract does not specify the diagnostic criteria used to define sensory impairments (such as objective testing versus self-report) or whether corrective interventions (hearing aids, corrective lenses) modified the observed risks. Genetic datasets were drawn from European-ancestry populations (UK Biobank and FinnGen), limiting generalizability to other ancestries.