Population Attributable Fraction of Incident Dementia Associated With Hearing Loss.

Importance: Hearing loss treatment delays cognitive decline in high-risk older adults. The preventive potential of addressing hearing loss on incident dementia in a community-based population of older adults, and whether it varies by method of hearing loss measurement, is unknown.

Objective: To calculate the population attributable fraction of incident dementia associated with hearing loss in older adults and to investigate differences by age, sex, self-reported race, and method of hearing loss measurement.

Design, setting, and participants: This prospective cohort study was part of the Atherosclerosis Risk in Communities Neurocognitive Study (ARIC-NCS) and had up to 8 years of follow-up (2011-2019). The 4 ARIC field centers in the study included Jackson, Mississippi; Forsyth County, North Carolina; the Minneapolis suburbs, Minnesota; and Washington County, Maryland. Community-dwelling older adults aged 66 to 90 years without dementia at baseline who underwent a hearing assessment at ARIC-NCS visit 6 (2016-2017) were included in the analysis. Data analysis took place between June 2022 and July 2024.

Exposures: Hearing loss measured objectively (audiometric) and subjectively (self-reported).

Main outcomes and measures: The main outcome was incident dementia (standardized algorithmic diagnosis with expert panel review). The population attributable fractions of dementia from both audiometric and self-reported hearing loss were calculated in the same participants, which quantified the maximum proportion of dementia risk in the population that can be attributed to hearing loss.

Results: Among 2946 participants (mean [SD] age, 74.9 [4.6] years; 1751 [59.4] female; 637 Black [21.6%] and 2309 White [78.4%] individuals), 1947 participants (66.1%) had audiometric hearing loss, and 1097 (37.2%) had self-reported hearing loss. The population attributable fraction of dementia from any audiometric hearing loss was 32.0% (95% CI, 11.0%-46.5%). Population attributable fractions were similar by hearing loss severity (mild HL: 16.2% [95% CI, 4.2%-24.2%]; moderate or greater HL: 16.6% [95% CI, 3.9%-24.3%]). Self-reported hearing loss was not associated with an increased risk for dementia, so the population attributable fraction was not quantifiable. Population attributable fractions from audiometric hearing loss were larger among those who were 75 years and older (30.5% [95% CI, -5.8% to 53.1%]), female (30.8% [95% CI, 5.9%-47.1%]), and White (27.8% [95% CI, -6.0% to 49.8%]), relative to those who were younger than 75 years, male, and Black.

Conclusions and relevance: This cohort study suggests that treating hearing loss might delay dementia for a large number of older adults. Public health interventions targeting clinically significant audiometric hearing loss might have broad benefits for dementia prevention. Future research quantifying population attributable fractions should carefully consider which measures are used to define hearing loss, as self-reporting may underestimate hearing-associated dementia risk.