Summary: People with hearing loss who do not use a hearing aid are at increased risk of developing dementia than those who use hearing aids, a new study reports.
Source: The Lancet
People experiencing hearing loss who are not using a hearing aid may have a higher risk of dementia than people without hearing loss, suggests a new study published in The Lancet Public Health journal. However, using a hearing aid may reduce this risk to the same level as people without hearing loss.
Dementia and hearing loss are common conditions among older adults. The Lancet Commission on dementia prevention, intervention, and care, published in 2020, suggested that hearing loss may be linked to around 8% of worldwide dementia cases, therefore, addressing hearing impairment could be a crucial way to reduce the global burden of dementia.
“The evidence is building that hearing loss may be the most impactful modifiable risk factor for dementia in mid-life, but the effectiveness of hearing aid use on reducing the risk of dementia in the real world has remained unclear.
“Our study provides the best evidence to date to suggest that hearing aids could be a minimally invasive, cost-effective treatment to mitigate the potential impact of hearing loss on dementia,” says corresponding author Prof. Dongshan Zhu, Shandong University (China).
The researchers looked at data from 437,704 people who were part of the UK Biobank database. Information on the presence of hearing loss and use of hearing aids was collected via self-reported questionnaires, and dementia diagnoses were determined using hospital records and death register data.
The average age of study participant at recruitment was 56 years old, and the average follow-up time was 12 years.
Around three-quarters of the participants (325,882/437,704) had no hearing loss, and the remaining one-quarter (111,822) had some level of hearing loss. Among those with hearing loss, 11.7% (13,092 / 111,822) used hearing aids.
After controlling for other factors, the study suggests that, compared to participants with normal hearing, people with hearing loss not using hearing aids had a 42% higher risk of all-cause dementia, while no increased risk was found in people with hearing loss who used hearing aids.
This is approximately equivalent to a 1.7% risk of dementia in people with hearing loss who are not using hearing aids, compared to 1.2% among those without hearing loss or who are experiencing hearing loss but using hearing aids.
“Close to four-fifths of people experiencing hearing loss do not use hearing aids in the UK. Hearing loss may begin early in one’s 40s, and there is evidence that gradual cognitive decline before a dementia diagnosis can last 20 to 25 years.
“Our findings highlight the urgent need for the early introduction of hearing aids when someone starts to experience hearing impairment. A group effort from across society is necessary, including raising awareness of hearing loss and the potential links with dementia, increasing accessibility to hearing aids by reducing cost, and more support for primary care workers to screen for hearing impairment, raise awareness, and deliver treatment such as fitting hearing aids,” says Dongshan Zhu.
The researchers also analysed how other factors, including loneliness, social isolation, and depressive symptoms, might impact the association between hearing loss and dementia. The study analysis suggests that less than 8% of the association between hearing aid use and decreased dementia risk could be removed by improving psychosocial problems.
The authors say this indicates the association between hearing aid use and protection from increased dementia is likely mostly due to direct effects from hearing aids rather than the investigated indirect causes.
“The underlying pathways which may link hearing aid use and reduced dementia risk are unclear. Further research is needed to establish a causal relationship and the presence of underlying pathways,” says study author Dr Fan Jiang, Shandong University (China).
The authors acknowledge some limitations to the study, including that self-reporting is at risk of bias and that, as this study is observational, the association between hearing loss and dementia might be due to reverse causation through neurodegeneration or other shared mechanisms.
Additionally, although many cofactors were accounted for, there might be unmeasured factors, such as those who used hearing aids potentially also taking more care of their health than those who did not.
Lastly, most UK Biobank participants are white, and very few participants were born deaf or experienced hearing loss before acquiring spoken language, which may limit the generalisability of the findings to other ethnicities and people with limited hearing using sign language.
Writing in a Linked Comment, Prof Gill Livingston and Dr Sergi Costafreda, University College London, who were not involved in this research, said: “With the addition of Jiang and colleagues’ work, the evidence that hearing aids are a powerful tool to reduce the risk of dementia in people with hearing loss, is as good as possible without randomised controlled trials, which might not be practically possible or ethical because people with hearing loss should not be stopped from using effective treatments.
“Dementia is not only an illness that affects the individual and their family but can also be expensive. However, using hearing aids to prevent dementia has been found to be cost-effective and cost-saving. In the USA, hearing aids have become available to purchase over the counter, thus making them more accessible.
“The evidence is compelling that treating hearing loss is a promising way of reducing dementia risk. This is the time to increase awareness of and detection of hearing loss, as well as the acceptability and usability of hearing aids.”
Funding: This study was funded by the National Natural Science Foundation of China and Shandong Province, Taishan Scholars Project, China Medical Board and China Postdoctoral Science Foundation.
About this dementia research news
Author: Press Office
Source: The Lancet
Contact: Press Office – The Lancet
Image: The image is in the public domain
Original Research: Open access.
“Association between hearing aid use and all-cause and cause-specific dementia: an analysis of the UK Biobank cohort” by Dongshan Zhu et al. Lancet Public Health
Abstract
Association between hearing aid use and all-cause and cause-specific dementia: an analysis of the UK Biobank cohort
Background
Dementia and hearing loss are both highly prevalent conditions among older adults. We aimed to examine the association between hearing aid use and risk of all-cause and cause-specific dementia among middle-aged and older-aged adults, and to explore the roles of mediators and moderators in their association.
Methods
We used data from the UK Biobank, a population-based cohort study, which recruited adults aged 40–69 years between 2006 and 2010 across 22 centres in England, Scotland, and Wales. We used Cox proportional hazards models to estimate hazard ratios (HRs) and 95% CIs between self-reported hearing aid use status (hearing loss with or without hearing aids) at baseline and risk of dementia (all-cause dementia, Alzheimer’s disease, vascular dementia, and non-Alzheimer’s disease non-vascular dementia). Dementia diagnoses were ascertained using hospital records and death-register data. We also analysed the roles of mediators (self-reported social isolation, loneliness, and mood) and moderators (self-reported education and income, smoking, morbidity, and measured APOE allele status).
Findings
After the exclusion of people who did not answer the question on hearing difficulties (n=25 081 [5·0%]) and those with dementia at baseline visit (n=283 [0·1%]), we included 437 704 people in the analyses. Compared with participants without hearing loss, people with hearing loss without hearing aids had an increased risk of all-cause dementia (HR 1·42 [95% CI 1·29–1·56]); we found no increased risk in people with hearing loss with hearing aids (1·04 [0·98–1·10]). The positive association of hearing aid use was observed in all-cause dementia and cause-specific dementia subtypes (Alzheimer’s disease, vascular dementia, and non-Alzheimer’s disease non-vascular dementia). The attributable risk proportion of dementia for hearing loss was estimated to be 29·6%. Of the total association between hearing aid use and all-cause dementia, 1·5% was mediated by reducing social isolation, 2·3% by reducing loneliness, and 7·1% by reducing depressed mood.
Interpretation
In people with hearing loss, hearing aid use is associated with a risk of dementia of a similar level to that of people without hearing loss. With the postulation that up to 8% of dementia cases could be prevented with proper hearing loss management, our findings highlight the urgent need to take measures to address hearing loss to improve cognitive decline.
Funding
National Natural Science Foundation of China and Shandong Province, Taishan Scholars Project, China Medical Board, and China Postdoctoral Science Foundation.
