Investigators also found that even mild hearing loss was associated with increased dementia risk, although it was not statistically significant, and that hearing aid use was tied to a 32% decrease in dementia prevalence.
“Every 10-decibel increase in hearing loss was associated with 16% greater prevalence of dementia, such that prevalence of dementia in older adults with moderate or greater hearing loss was 61% higher than prevalence in those with normal hearing,” lead investigator Alison Huang, PhD, senior research associate in epidemiology at Johns Hopkins Bloomberg School of Public Health and core faculty in the Cochlear Center for Hearing and Public Health, Baltimore, Md., told this news organization.
The findings were published online in JAMA.
For the study, researchers analyzed data on 2,413 community-dwelling participants in the National Health and Aging Trends Study, a nationally representative, continuous panel study of U.S. Medicare beneficiaries aged 65 and older.
Data from the study were collected during in-home interviews, setting it apart from previous work that relied on data collected in a clinical setting, Dr. Huang said.
“This study was able to capture more vulnerable populations, such as the oldest old and older adults with disabilities, typically excluded from prior epidemiologic studies of the hearing loss–dementia association that use clinic-based data collection, which only captures people who have the ability and means to get to clinics,” Dr. Huang said.
Weighted hearing loss prevalence was 36.7% for mild and 29.8% for moderate to severe hearing loss, and weighted prevalence of dementia was 10.3%.
Those with moderate to severe hearing loss were 61% more likely to have dementia than those with normal hearing (prevalence ratio, 1.61; 95% confidence interval, 1.09-2.38).
Dementia prevalence increased with increasing severity of hearing loss: normal hearing: 6.19% (95% CI, 4.31-8.80); mild hearing loss: 8.93% (95% CI, 6.99-11.34); moderate/severe hearing loss: 16.52% (95% CI, 13.81-19.64). But only moderate to severe hearing loss showed a statistically significant association with dementia (P = .02).
Dementia prevalence increased 16% per 10-decibel increase in hearing loss (prevalence ratio 1.16; P < .001).
Among the 853 individuals in the study with moderate to severe hearing loss, those who used hearing aids (n = 414) had a 32% lower risk of dementia compared with those who didn’t use assistive devices (prevalence ratio, 0.68; 95% CI, 0.47-1.00). This news organization last month reported on similar data published in JAMA Neurology suggesting that hearing aids reduce dementia risk.
“With this study, we were able to refine our understanding of the strength of the hearing loss–dementia association in a study more representative of older adults in the United States,” said Dr. Huang.
Commenting on the findings, Justin S. Golub, MD, associate professor in the department of otolaryngology–head and neck surgery at Columbia University, New York, said the study supports earlier research and suggests a “robust” association between hearing loss and dementia.
“The particular advantage of this study was that it was high quality and nationally representative,” Dr. Golub said. “It is also among a smaller set of studies that have shown hearing aid use to be associated with lower risk of dementia.”
Although not statistically significant, researchers did find increasing prevalence of dementia among people with only mild hearing loss, and clinicians should take note, said Dr. Golub, who was not involved with this study.
“We would expect the relationship between mild hearing loss and dementia to be weaker than severe hearing loss and dementia and, as a result, it might take more participants to show an association among the mild group,” Dr. Golub said.
“Even though this particular study did not specifically find a relationship between mild hearing loss and dementia, I would still recommend people to start treating their hearing loss when it is early,” Dr. Golub added.
The study was funded by the National Institute on Aging. Dr. Golub reports no relevant financial relationships.
A version of this article first appeared on Medscape.com.