Association of Hearing Aids and Cochlear Implants With Cognitive Decline and Dementia: A Systematic Review and Meta-analysis.
Level 2 - randomized trial
Systematic review and meta-analysis composed predominantly of observational cohort studies rather than randomized controlled trials
PubMed 36469314 · doi:10.1001/jamaneurol.2022.4427
What was done
A systematic review and meta-analysis of PubMed, Embase, and Cochrane databases through July 23, 2021, conducted according to PRISMA guidelines. The authors identified randomized clinical trials and observational studies examining the association between hearing restorative devices (hearing aids and cochlear implants) and cognitive decline, cognitive impairment, or dementia in individuals with hearing loss. Maximally adjusted hazard ratios (HRs) were pooled for dichotomous outcomes, and ratio of means was calculated for continuous cognitive test outcomes.
What was found
The review included 31 studies (25 observational studies, 6 trials) with 137,484 participants, with 19 included in quantitative analyses: - Long-term cognitive decline (8 studies, n = 126,903, follow-up 2 to 25 years): Hearing aid users had a significantly lower hazard of any cognitive decline compared with participants with uncorrected hearing loss (HR, 0.81; 95% CI, 0.76-0.87; I2 = 0%). - Short-term cognitive scores (11 studies, n = 568): Hearing restoration was associated with a 3% improvement in short-term cognitive test scores (ratio of means, 1.03; 95% CI, 1.02-1.04; I2 = 0%).
Why it matters
This meta-analysis links hearing restorative devices to a 19% reduction in the hazard of long-term cognitive decline, supporting hearing intervention as a key target in dementia prevention.
Limits
The long-term evidence relies predominantly on observational cohorts subject to residual confounding (such as socioeconomic status and health-seeking behavior). The short-term cognitive benefit analysis had a small total sample size (n = 568), and immediate test score changes may reflect improved auditory comprehension during cognitive testing rather than underlying neurocognitive improvement.
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