ADULTS with hearing loss are 42 per cent less likely to develop dementia if they use a hearing aid, according to a major new study.

The research suggests that addressing hearing impairment effectively at an early stage could be one of the simplest and most cost-effective ways of reducing the risk of cognitive decline.

Scientists compared outcomes by tracking 437,704 participants whose data is stored in the UK Biobank.

The average age of participants when the study began was 56, with a follow-up time of 12 years.

Participants had self-reported whether they suffered from hearing loss and used a hearing aid, with information on dementia diagnoses gathered using hospital records and deaths registrations.

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Of the participants, 325,882 had no hearing loss while 111,822 had some level of hearing loss.

Among those with hearing loss, fewer than 12% (13,092) used hearing aids.

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After controlling for other factors, the study found a 1.7% risk of dementia in people with hearing loss who were not using hearing aids.

By contrast, among people with hearing loss who did use a hearing aid, the risk of dementia - 1.2% - was no different to people with normal hearing.

The results, published today in the journal Lancet Public Health, suggest that failing to use a hearing aid is associated with a 42% increased risk of dementia onset.

The Herald:

The study's author, Professor Dongshan Zhu of Shandong University in China, said:

“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."

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The findings build on previous work by the Lancet Commission on dementia prevention, published in 2020, which indicated that hearing loss may be linked to around 8% of worldwide dementia cases.

Prof Dongshan added: “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."

The authors caution that further research is needed to understand whether there is a causal relationship between hearing loss and dementia.

However, they said that their analysis suggests that hearing aids appear to have a direct protective role - as opposed to simply mitigating problems such as loneliness and social isolation.

The Herald:

Tara Spires-Jones, a professor of neurodegeneration and deputy director of the Centre for Discovery Brain Sciences at Edinburgh University, said: "This type of study cannot prove conclusively that hearing loss causes dementia.

"For example, it is possible that people who are already in the very early stages of disease are less likely to seek help for hearing loss.

"However, on balance, this study and the rest of the data in the field indicate that keeping your brain healthy and engaged reduces dementia risk.

"I agree with the conclusions of the paper that it is important to help people with hearing loss to get effective hearing aids to help keep their brains engaged through allowing richer social interactions.”

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In an editorial accompanying the research, Professor Gill Livingston and Dr Sergi Costafreda of University College London - who were not involved in the study - said it provided the best evidence possible that hearing aids "are a powerful tool to reduce the risk of dementia in people with hearing loss".

They noted that it would not be "practically possible or ethical" to carry out a randomised control trial into the link between hearing aids and dementia because "people with hearing loss should not be stopped from using effective treatments".

They added: "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.”