Abstract
This study assesses the association of audiometric hearing loss and hearing aid use with dementia among community-dwelling older US Medicare beneficiaries.
Hearing loss accounts for 8% of global dementia cases, rendering it the largest modifiable risk factor for dementia at a population level.1 However, there are few nationally representative estimates of the association between hearing loss and dementia among older adults in the US. Previous estimates were vulnerable to selection bias and typically used self-reported data, which may underestimate hearing and dementia and not reflect the true association on a national scale.2,3 In addition, hearing aid use may potentially lower dementia risk among older adults with hearing loss, but evidence is limited and mixed.4,5 We estimated the cross-sectional association of audiometric hearing loss and hearing aid use with dementia among community-dwelling older adults using a nationally representative data set of US Medicare beneficiaries.
Methods
Data come from community-dwelling participants (nursing home/residential care residents were excluded [no cognitive data]) of Round 11 (2021; 94% response rate) of the National Health and Aging Trends Study (NHATS), a nationally representative, continuous panel study of US Medicare beneficiaries older than 65 years. NHATS is a probability-based sample with oversampling by age (≥90 years) and race (Black individuals). Since 2011, data were collected annually via in-home interviews with sample replenishment in 2015.
Air-conduction pure tone audiometry used an electronic tablet-based portable audiometer (Shoebox Ltd). A speech-frequency pure tone average (PTA) in the better-hearing ear was calculated as the mean of 4 frequencies (500, 1000, 2000, and 4000 Hz) most important for speech understanding. The PTA was modeled continuously and categorically (normal: ≤25 dB; mild: 26-40 dB; and moderate/severe: >40 dB). Hearing aid use was self-reported. The NHATS algorithm classifies participants as having dementia if they scored less than or equal to 1.5 SDs from the mean of self-respondents in 1 or more cognitive domain (memory, orientation, executive function), had a self- or proxy-reported dementia diagnosis, or had an AD8 Dementia Screening Interview score indicating probable dementia.6 Covariates included age, sex, education, race and ethnicity (see footnote c in Table 1), history of smoking, and number of chronic conditions (diabetes, hypertension, stroke, myocardial infarction, heart disease, lung disease, or cancer).
Table 1. Weighted Characteristics of Participants by Hearing Loss, National Health and Aging Trends Study, Round 11, 2021.
| Characteristics | Unweighted No. (N = 2413) | Weighted % (95% CI) | |||
|---|---|---|---|---|---|
| Total | Normal hearinga | Mild hearing lossa | Moderate to severe hearing lossa | ||
| Overall | 100.00 | 33.47 (30.60-36.46) | 36.74 (34.67-38.86) | 29.79 (27.47-32.22) | |
| Age, y | |||||
| 70-74 | 359 | 30.63 (28.18-33.19) | 44.08 (39.10-49.19) | 28.42 (24.73-32.41) | 18.25 (14.22-23.10) |
| 75-79 | 769 | 34.38 (31.65-37.23) | 38.01 (33.20-43.08) | 36.44 (32.50-40.56) | 27.78 (23.03-33.08) |
| 80-84 | 622 | 19.77 (18.05-21.62) | 14.48 (12.00-17.38) | 21.39 (18.66-24.40) | 23.72 (20.23-27.60) |
| 85-89 | 412 | 10.43 (9.29-11.68) | 2.66 (1.81-3.91) | 11.26 (9.34-13.51) | 18.12 (15.47-21.11) |
| ≥90 | 251 | 4.79 (4.13-5.54) | 0.75 (0.39-1.45) | 2.50 (1.79-3.47) | 12.14 (10.30-14.25) |
| Sex | |||||
| Female | 1347 | 53.89 (51.26-56.49) | 62.68 (56.59-68.40) | 53.37 (48.90-57.79) | 44.65 (40.50-48.87) |
| Male | 1066 | 46.11 (43.51-48.74) | 37.32 (31.60-43.41) | 46.63 (42.21-51.10) | 55.35 (51.13-59.50) |
| Race and ethnicityb | |||||
| Black, non-Hispanic | 453 | 7.16 (6.07-8.44) | 9.18 (7.11-11.79) | 7.47 (5.96-9.33) | 4.51 (3.51-5.79) |
| Hispanic | 110 | 6.54 (4.67-9.08) | 7.06 (4.43-11.08) | 5.18 (3.25-8.14) | 7.63 (4.88-11.75) |
| White, non-Hispanic | 1790 | 82.34 (79.23-85.08) | 79.29 (73.94-83.78) | 82.85 (79.25-85.93) | 85.15 (81.13-88.44) |
| Other | 60 | 3.95 (2.85-5.47) | 4.47 (2.41-8.12) | 4.50 (3.05-6.60) | 2.71 (1.57-4.64) |
| Education | |||||
| Less than high school | 355 | 11.87 (10.15-13.83) | 7.28 (5.23-10.06) | 11.40 (9.36-13.81) | 17.60 (14.02-21.87) |
| High school graduate | 617 | 24.02 (21.58-26.63) | 18.94 (15.55-22.87) | 24.60 (21.31-28.22) | 28.99 (25.01-33.33) |
| More than high school | 1441 | 64.11 (60.83-67.27) | 73.78 (69.42-77.71) | 64.00 (59.60-68.17) | 53.40 (48.84-57.91) |
| Ever smoked | 1185 | 49.79 (47.28-52.31) | 43.50 (39.84-47.23) | 52.77 (48.23-57.26) | 53.19 (48.78-57.56) |
| No. of health conditionsc | |||||
| 0 | 332 | 16.46 (14.79-18.29) | 18.24 (14.40-22.83) | 16.11 (13.44-19.19) | 14.91 (12.54-17.63) |
| 1 | 808 | 34.82 (32.41-37.31) | 40.02 (36.05-44.13) | 32.50 (28.57-36.69) | 31.85 (27.81-36.18) |
| 2 | 738 | 28.23 (26.01-30.57) | 25.03 (21.30-29.17) | 28.99 (25.90-32.30) | 30.89 (26.63-35.51) |
| 3 | 392 | 15.08 (13.44-16.88) | 13.23 (10.63-16.35) | 15.84 (13.01-19.17) | 16.20 (13.39-19.47) |
| ≥4 | 143 | 5.40 (4.51-6.46) | 3.47 (2.12-5.63) | 6.56 (5.00-8.54) | 6.15 (4.73-7.96) |
| Dementia | 332 | 10.27 (8.90-11.83) | 6.19 (4.31-8.80) | 8.93 (6.99-11.34) | 16.52 (13.81-19.64) |
| Hearing aid use | 543 | 20.29 (18.16-22.60) | 1.72 (0.84-3.47) | 13.32 (10.38-16.95) | 49.74 (45.33-54.16) |
Hearing loss was defined according to better-ear 4-frequency pure tone average (normal hearing: ≤25 dB; mild hearing loss: 26-40 dB; moderate to severe hearing loss: >40 dB).
Race and ethnicity were self-reported. The “other” category of race includes participants who self-identified as Alaska Native, American Indian, Asian, Native Hawaiian, Pacific Islander, other specified race, or more than 1 race, non-Hispanic. Race and ethnicity were included because of the known racial and ethnic differences in prevalence of hearing loss and dementia.
Health conditions included high blood pressure, diabetes, myocardial infarction, heart disease, stroke, lung disease, and cancer.
Poisson regression adjusted for demographic and clinical covariates estimated dementia prevalence ratios. Secondary analysis investigated hearing aid use and dementia among participants with moderate to severe hearing loss. Analyses were weighted and conducted using Stata version 17 with a 2-sided P ≤ .05 considered statistically significant. The Johns Hopkins University institutional review board approved this study. Written informed consent was obtained from all study participants by NHATS investigators.
Results
Among 2413 participants, 1285 (53.3%) were aged 80 years or older and 1347 (55.8%) were female; 453 (18.8%) were non-Hispanic Black, 110 (4.5%) were Hispanic, and 1790 (74.2%) were non-Hispanic White. The weighted prevalence of dementia was 10.27% (95% CI, 8.90%-11.83%) and increased with increasing severity of hearing loss (normal: 6.19% [95% CI, 4.31%-8.80%]; mild: 8.93% [95% CI, 6.99%-11.34%]; moderate/severe: 16.52% [95% CI, 13.81%-19.64%]). Weighted hearing loss prevalence was 36.74% (95% CI, 34.67%-38.86%) for mild and 29.79% (95% CI, 27.47%-32.22%) for moderate to severe hearing loss. Participants with moderate to severe hearing loss were more likely to be older, male, and White and to have lower education levels compared with participants with mild hearing loss or normal hearing (Table 1).
Dementia prevalence among participants with moderate to severe hearing loss was higher than prevalence among participants with normal hearing (prevalence ratio, 1.61 [95% CI, 1.09-2.38]) (Table 2). This association was consistent with analyses modeling PTA continuously (per 10-dB worse hearing loss) (prevalence ratio, 1.16 [95% CI, 1.07-1.26]). Among 853 participants with moderate to severe hearing loss, hearing aid use (n = 414) was associated with lower prevalence of dementia compared with no hearing aid use (prevalence ratio, 0.68 [95% CI, 0.47-1.00]) (Table 2).
Table 2. Multivariable-Adjusted Association Between Hearing Loss, Hearing Aid Use, and Dementia, National Health and Aging Trends Study, Round 11, 2021.
| Unweighted No. | Weighted prevalence of dementia (95% CI) | Prevalence ratio (95% CI)a | P value | |
|---|---|---|---|---|
| Audiometric hearing | 2413 | |||
| Normal hearing | 674 | 6.19 (4.31-8.80) | [Reference] | |
| Mild hearing loss | 886 | 8.93 (6.99-11.34) | 1.08 (0.72-1.63) | .71 |
| Moderate to severe hearing lossb | 853 | 16.52 (13.81-19.64) | 1.61 (1.09-2.38) | .02 |
| P value for trend | .01 | |||
| Per 10-dB worse hearing | 1.16 (1.07-1.26) | <.001 | ||
| Hearing aid usec | 853 | |||
| No | 439 | 21.53 (16.66-27.37) | [Reference] | |
| Yes | 414 | 11.46 (8.79-14.82) | 0.68 (0.47-1.00) | .05 |
Models are adjusted for age, sex, race and ethnicity, education, smoking, and number of health conditions.
Hearing loss was defined according to better-ear 4-frequency pure tone average (normal hearing: ≤25 dB; mild hearing loss: 26-40 dB; moderate to severe hearing loss: >40 dB).
Hearing aid use and dementia prevalence were assessed only among participants with moderate to severe hearing loss, defined as better-ear 4-frequency pure tone average >40 dB.
Discussion
In a nationally representative sample of older adults in the US, moderate to severe hearing loss was associated with higher prevalence of dementia compared with normal hearing. Hearing aid use was associated with lower dementia prevalence, supporting public health action to improve hearing care access, including increased availability of affordable hearing aids (Over the Counter Hearing Aid Act [HR 2430, §934]) and Medicare provision of hearing aids and rehabilitation services. Study limitations include the cross-sectional study design and exclusion of nursing home/residential care residents. Mediation analyses to characterize mechanisms underlying the association and randomized trials to determine the effects of hearing interventions on reducing dementia risk are needed.
Section Editors: Jody W. Zylke, MD, Deputy Editor; Kristin Walter, MD, Senior Editor.
Data Sharing Statement
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Data Sharing Statement