Hearing loss is an important component of healthy ageing. Yet, the current hype is focused on the association between hearing loss and cognition, in particular, risk of dementia. One could be forgiven for thinking it is only worth addressing hearing loss because of the risk of dementia. Is the hype justified or have we been hypnotised by the newsworthiness of dementia?
By Kevin J Munro and Piers Dawes.
There is a well-established association between sensory function and cognition in the general population: people with poorer sensory function tend to have poorer cognitive ability. Also, people with severe hearing loss are more likely to develop dementia.
There are plausible explanations for why hearing loss may cause cognitive decline, including direct changes in brain structure due to impoverished auditory input or increased cognitive demand, or indirectly due to social isolation and withdrawal. A review on dementia prevention, intervention, and care by researchers in 2020 (Livingston et al) concluded that eliminating, or fully addressing hearing loss, could potentially reduce the overall number of cases of dementia.
It is an appealing prospect if hearing loss impacts on cognition, because avoiding hearing loss or treating it might reduce the risk of dementia. However, the association between hearing loss and cognition does not mean that one causes the other. For example, there is an association between sales of ice cream and swimwear, but warm summer weather might explain the increase in the sale of both. A common cause may be responsible for the association between hearing and cognition – for example, hypertension, obesity, smoking and air pollution are all risk factors for both dementia and hearing loss.
Comparing hearing aid users and non-users
A study in 2023, based on analysis of a large UK dataset reported that hearing aid use was associated with a substantial reduction in risk of dementia compared to people who self-reported hearing loss but did not use hearing aids (Jiang et al). The article was published to a fanfare of publicity and media interest extolling the results. But then, rather quietly, the journal retracted the article, and the accompanying editorials because the authors had made an error. In fact, the risk of dementia was higher for hearing aid users than the non-hearing aid users. A likely explanation is that people with more severe hearing loss are more likely to use hearing aids and more severe hearing loss is associated with an increased dementia risk. You can find details on how the retraction came about here. It remains to be seen if the corrected findings and interpretation will be reported, let alone receive the same publicity.
Overcoming the limitations of observational studies
Research trials that randomly allocate participants to the intervention and control groups minimise potential biases. There are few high-quality randomised trials in hearing research.
An exception is the ACHIEVE study by Frank Lin and colleagues in 2023 – it is impressive in terms of rigour, scope, and potential impact. Participants were randomly allocated to a comprehensive hearing intervention or a control of health education. The primary outcome reported in ACHIEVE was changes in cognition after three years of intervention. And the finding: no difference in cognitive decline between the two groups.
The authors reported an additional finding showing less cognitive decline in a subgroup of participants who were reported to be at high risk of cognitive decline. This finding is surprising because it does not replicate the well-known:
- association between sensory function and cognition that many studies have reported in the general population, and
- decline in cognition with increasing severity of hearing loss.
Despite the intense interest and hype surrounding the topic, hearing professionals, other health professionals and policymakers would be wise to treat the finding with caution. For a more extensive discussion, see Dawes and Munro (2024).
There are multiple dangers when hype is unchecked. The desire for something to be true might stifle critical thinking and result in:
- Hearing loss not being considered critical in its own right, despite its importance for healthy ageing and the well-known benefit of hearing aids in reducing hearing disability and improving communication.
- Misunderstanding that hearing aids do not affect the underlying pathology of dementia and the progress of cognitive decline, but they may reduce the risk of dementia by supporting independent daily functioning.
- People less likely to seek help for hearing loss because of scare tactics and stigma about dementia.
- Loss of interest in hearing loss by policymakers and funders if the causal links with dementia are not proven, despite the much-needed attention to timely assessment and management of hearing loss for people living with dementia.
In summary, hearing loss and dementia are strongly associated but claims that hearing loss causes dementia, or hearing intervention reduces the risk, are not based on current available evidence.
Hype and negative messaging have the potential to undermine the importance of hearing per se. For a wider discussion of the issues, see Dawes and Munro (2024) on which this article is based.
Take-home messages
For hearing care professionals, professional bodies and advocacy bodies
Raise awareness of:
- Prevalence and impact of untreated hearing loss on quality-of-life
- Proven benefits of hearing interventions.
- Avoid negative messaging about associations between hearing loss and dementia risk.
For other health professionals
- Holistic care includes addressing hearing needs.
- Communication is important in healthcare delivery and individuals’ quality-of-life.
For policy-makers
Hearing interventions:
- Facilitate healthy aging
- Maintain independent functioning
- Reduce healthcare costs.
About the Authors
Kevin J Munro is Ewing Professor of Audiology, Manchester Centre for Audiology and Deafness, School of Health Sciences, University of Manchester, UK.
Piers Dawes is Professor of Audiology, Centre for Hearing Research, School of Health and Rehabilitation Sciences, University of Queensland, Australia.