Adult-onset hearing loss and incident cognitive impairment and dementia - A systematic review and meta-analysis of cohort studies.
Level 3 - non-randomized controlled study
Systematic review and meta-analysis of cohort studies
PubMed 38788800 · doi:10.1016/j.arr.2024.102346
What was done
Systematic review and meta-analysis of 50 cohort studies (N=1,548,754) evaluating adult-onset hearing loss as a risk factor for incident cognitive impairment and dementia. Inclusion required cohort designs with participants free of dementia at baseline, baseline hearing assessments, at least 2 years of follow-up, and incident cognitive outcomes. Random-effects models, subgroup analyses, and meta-regressions were used to examine dose-response relationships, dementia subtypes, and potential moderators.
What was found
Hearing loss was associated with increased risk of incident dementia (HR=1.35, 95% CI 1.26–1.45), mild cognitive impairment (HR=1.29, 95% CI 1.11–1.50), unspecified cognitive decline (HR=1.29, 95% CI 1.17–1.42), and Alzheimer's disease dementia (HR=1.56, 95% CI 1.30–1.87), but was not significantly associated with vascular dementia (HR=1.30, 95% CI 0.83–2.05). A dose-response relationship was observed: each 10-decibel worsening in hearing was associated with a 16% increase in dementia risk (95% CI 1.07–1.27). Effect sizes did not vary across potential moderators.
Why it matters
Provides large-scale longitudinal evidence linking adult-onset hearing loss to incident cognitive impairment and Alzheimer's dementia in a dose-dependent manner.
Limits
All included studies were observational cohorts, precluding causal inference. The abstract does not specify the methods of hearing assessment (objective audiometry vs. self-report), average follow-up duration across studies, or the impact of hearing interventions (such as hearing aids) on risk.