It has long been thought by ENT surgeons and Audiologists that hearing loss and cognitive decline and dementia frequently accompany each other and that the hearing loss worsened the individual’s rate of decline. It was an intuitive connection but it was unknown whether the relationship was just an association or whether there was some causal link between the reduction of hearing input and the cognitive decline. Many non ENT physicians thought the hearing loss was just a part of the general decline and that some people simply deteriorated more quickly than others.
A paper from Frank Lin in 2013 entitled “Hearing loss and cognitive decline among older adults concluded: “hearing loss is independently associated with accelerated cognitive decline and incident cognitive impairment in community-dwelling older adults. Further studies investigating mechanistic basis of this association and whether hearing rehabilitative interventions could affect cognitive decline are needed.”
Those studies took some time to be published because of the very long time course and slow progression of both age-related hearing loss and mental decline. However, there are now several studies, recently published, that seem to confirm that hearing loss is causally related to an accelerated cognitive decline and that aiding the individual will slow that decline back to the same level of the non-hearing impaired individual. One of the more accessible papers from 2018 is from the SENSE group led by Maharani and based in Manchester, UK. The team reported in the Journal of the American Geriatrics Society. The group concluded: “hearing aids may have a mitigating effect on trajectories of cognitive decline in later life. Providing hearing aids or other rehabilitative services for hearing impairment much earlier in the course of hearing impairment may stem the worldwide rise of dementia.”
One of the strengths of this study was its long term nature spreading over 18 years and in the discussion the authors state: “our study shows a less steep decrease in episodic memory performance after beginning to use hearing aids than before using hearing aids. The slower rate of decline after beginning hearing aid use remains significant after taking attrition into account.”
The graph showing this slowing of the rate of decline is taken from the supplementary figures on the online version of the article.
Supplementary Figure S2. Predicted values of episodic memory using joint model before and after beginning to use hearing aids (time centred at using hearing aids) The scale across the bottom of the graph is in years.
This finding is echoed in the Lancet commission on “Dementia prevention, intervention and care: 2020 report.”
One of the relevant paragraphs states: Hearing aids A 25-year prospective study of 3777 people aged 65 years or older found increased dementia
incidence in those with self-reported hearing problems except in those using hearing aids.
Similarly, a cross–sectional study found hearing loss was only associated with worse cognition in those not using hearing aids. A US nationally representative survey of 2040 people older than 50 years, tested every two years for 18 years, found immediate and delayed recall deteriorated less after initiation of hearing aid use, adjusting for other risk factors.
Hearing aid use was the largest factor protecting from decline.
The long follow-up times in these prospective studies suggest hearing aid use is protective, rather than the possibility that those developing dementia are less likely to use hearing aids.
Hearing loss might result in cognitive decline through reduced cognitive stimulation.
In July 2024 the Lancet published the report of its Commission on Dementia Prevention, Intervention and care. The links to the report and a helpful synopsis are below.
https://doi.org/10.1016/S0140-6736(24)01296-0
https://doi.org/10.1016/S0140-6736(24)01546-0
[It is relatively easy to obtain free access to the reports. Follow the link and then register for free access with your e-mail and a password. The “Register for free” box is just above the “References” section. Sometimes clicking on the “Download Full Issue” in the box at the top right hand corner will down load the whole issue with the Dementia article included.]
As severity of hearing loss increases, dementia risk increases: all four studies that investigated dose–response between hearing and dementia risk reported that every 10 dB decrease in hearing ability increased dementia risk. The magnitude of this risk increase varied between studies, from a 4% increase to a 24% increase in dementia risk per 10 dB decrease in hearing ability. Even if the true figure lies somewhere between the two extremes
then this is, to my mind, significant and something that can eliminated by appropriate hearing aids.
In the general population over the age of 50 there is a natural loss of 2 dB per year on averages at the higher frequencies. Around any average value there is a “range” and some people loose more than average and some less.
The observational evidence of the benefits of hearing aids for dementia risk is increasing.
Even if only the studies with long follow-up are considered, to reduce the chance of reverse causality, the evidence on hearing aids reducing dementia risk is consistent and supportive.
Implementing the use of hearing aids, if effective in preventing dementia, would likely be cost saving to the individual, the family and the State.
Below is the diagram taken from the 2024 report in the Lancet assessing the contributory factors to dementia. Overall these factors make up about 45% of the overall number of cases of Dementia with the other 55% presumably having genetic and metabolic causes that are yet to be identified.
The graphic shows the contributors to those causes of dementia which are potentially modifiable. Hearing loss is the biggest contributory factor in midlife and depression in midlife and social isolation in later life which are all, in turn, linked with hearing loss, contribute as other major factors.
Emily Ishak reported in 2025, an American study looking prospectively at 2946 people more than 65 years old and over an eight-year period. Any audiometric hearing loss – defined as averaged pure tone audiogram thresholds at 0.5, 1, 2 and 4kHz of more than 25dB – was
believed to contribute to the onset of dementia in 32% of this elderly population even taking into account the use of hearing aids for some of the time in some of the group. The analysis appears to be rigorous but this study was not designed to show that regular hearing aid use reduced the risk of dementia in those with the same degree of hearing loss who did not wear
hearing aids.
The authors concluded:
“In a large cohort of community-dwelling older adults with a mean age of 75 years, nearly 1 in 3 incident dementia cases could be attributed to clinically significant Hearing Loss.
Interventions for sensory health in late life might be associated with a broad benefit for cognitive health.”
In summary, recent long-term studies show a strong causal relation between poor hearing and rather quicker cognitive decline than occurs in better hearing groups and the ability to slow that decline by the provision of good quality hearing aids. The hearing aids in use in some of the trials would have been of relatively low technology compared to the current devices which have better high frequency responses, selectivity in background noise and ease of use.
Tony Wright, Spring 2025.
References.
Frank Lin et al. 2013
Hearing loss and cognitive decline among older adults
JAMA Intern Med. 2013 February 25; 173(4).
Maharani A et al. 2018.
Longitudinal Relationship Between Hearing Aid Use and Cognitive Function in Older
Americans
JAGS 66:1130–1136, 2018.
Emily Isha et al. 2025
Population Attributable Fraction of Incident Dementia Associated With Hearing Loss
JAMA Otolaryngology–Head&Neck Surgery Published online: jamaoto.2025.0192