Science

NIHR Evidence – What impact does hearing loss have on dementia risk?

From NIHR Evidence

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NIHR Evidence – What impact does hearing loss have on dementia risk?

19/02/2025

A comprehensive review of research explored the link between adult-onset hearing loss, dementia, and problems with thinking and memory (cognitive impairment). Researchers found that:

hearing loss was linked to an increased risk of mild to severe cognitive problems, including mild cognitive impairment and Alzheimer’s disease
hearing loss was not linked to an increased risk of vascular dementia
the greater the hearing loss, the higher the risk of dementia.

The findings support suggestions that addressing hearing loss might reduce the risk of some types of dementia.

More information about hearing loss can be found on the NHS website.

The issue: how harmful is hearing loss?

The Royal National Institute for Deaf People estimates that 18 million people in the UK have hearing loss in one or both ears. Some experts describe hearing loss as a modifiable risk factor for dementia, but previous findings are mixed. A 2022 systematic review found that people with hearing loss who use hearing aids or cochlear implants have a reduced risk of developing dementia. Similarly, a large randomised controlled trial found that hearing aids reduced the risk of cognitive decline by 48% in 70 – 84 year olds with untreated hearing loss (including people with low cognitive scores). However, hearing aids did not reduce dementia risk in those at low risk.

The current review pulled together previous research on hearing loss and dementia. Researchers assessed the link between hearing loss on dementia subtypes.

What’s new?

Researchers analysed 50 studies from the US, East Asia, Europe and Australia in a total of 1.5 million people. All studies explored the link between adult-onset hearing loss and cognitive outcomes, but outcomes were described in different ways (dementia for example, rather than Alzheimer’s disease).

The review considered the severity and type of cognitive impairment along with the degree of hearing loss; and looked at the impact of age and length of follow-up (at least 2 years for all participants). In half the studies, participants either self-reported hearing loss or had a history of hearing loss; in the remainder, they were assessed at the start of the study.

Those with hearing loss at the beginning of each study were compared to those with no hearing loss. Over the course of a study, people with hearing loss had:

an increased risk of dementia (35% increase in 30 studies) and Alzheimer’s disease (56% increase in 4 studies)
an increased risk of mild cognitive impairment (29% in 3 studies)
an increased risk of unspecified cognitive decline (also 29% increase in 9 studies)
no link between vascular dementia and hearing loss (in 3 studies).

The research suggested that:

both mild and moderate to severe hearing loss were associated with increased dementia risk (7 studies for each finding)
the greater the hearing loss, the greater the risk of cognitive decline (every 10 decibel decrease in hearing was associated with 16% increase in dementia risk; 2 studies)
the link between hearing loss and dementia did not vary according to age at the start of the study (35 studies), or length of follow-up (37 studies).

“We now have strong evidence that hearing loss is linked to cognitive decline, but most of this comes from studies that follow people over time rather than proving cause and effect. We know that addressing hearing loss helps people stay socially connected and maintain their quality of life as they age, and it may also play a key role in protecting cognitive health.

The next step is to confirm whether treating hearing loss can slow cognitive decline, and for that, we need a clinical trial. Since this research, we have been developing new ways to identify and treat hearing loss earlier, particularly in people with mild cognitive impairment. This could help audiologists and clinicians encourage hearing aid use as part of a broader dementia prevention strategy. Our next step is to test whether providing hearing aids early, with the right support for long-term use, can reduce dementia risk.”

Ruan-Ching Yu, Postdoctoral Research Fellow, University College London

Why is this important?

The findings support the suggestion that adult-onset hearing loss might be a cause of dementia. Results were consistent across studies, despite differences in the people included, and the type of cognitive impairment they looked at.

Adult-onset hearing loss can be treated, most often with hearing aids. Following on from this study, the researchers went on to explore the impact of wearing hearing aids on mild cognitive impairment.

What’s next?

The team has since included hearing loss as a risk factor for dementia in another NIHR-funded programme. The researchers developed an app (ENHANCE) which, with coaching support, aims to encourage people to adopt healthier lifestyles and reduce their risk of dementia. It targets hearing loss along with other risk factors such as high blood pressure, diabetes, physical inactivity and low mood. The app includes cognitive games to keep the mind active, educational health-related videos to encourage healthy behaviour, and tools for tracking health behaviours.