People with hearing loss who are not using a hearing aid may have a higher risk of dementia than people without hearing loss, research suggests.
But according to the new study, using a hearing aid may reduce this risk to the same level as people without hearing loss.
Researchers suggest the findings indicate that the devices could be a cheap way to reduce the potential impact of hearing loss on dementia.
They add that they also highlight the urgent need for the early introduction of hearing aids when someone starts to experience hearing impairment.
Professor Dongshan Zhu, from Shandong University, 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.”
The researchers looked at data from 437,704 people who were part of the UK Biobank study.
The average age of those recruited to the study was 56 years old, and the average follow-up time was 12 years.
According to the study, around three-quarters of people (325,882) 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.
The researchers found that compared to people with normal hearing, those with hearing loss not using hearing aids had a 42% higher risk of all-cause dementia.
There was no increased risk in people 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 the devices.
Prof Zhu said: “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.”
The study also looked at how other factors, including loneliness, social isolation, and depressive symptoms, might impact the association between hearing loss and dementia.
The findings, published in The Lancet Public Health journal, indicate 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.
Dr Charles Marshall, clinical senior lecturer in neurology, preventive neurology unit, Queen Mary University of London (QMUL), said: “Hearing aids produce slightly distorted sound, and the brain has to adapt to this in order for hearing aids to be helpful.
“People who are at risk of developing dementia in the future may have early changes in their brain that impair this adaptation, and this may lead to them choosing to not use hearing aids.
“This would confound the association, creating the appearance that hearing aids were reducing dementia risk, when actually their use was just identifying people with relatively healthy brains.
“Hopefully the evidence from this paper will lead to randomised trials of hearing aid use that will provide a stronger foundation for public health advice about whether correcting hearing loss might help to prevent dementia.”
Robert Howard, professor of old age psychiatry, UCL, said: “This is a large and well-conducted study, but we should always remember that association is not the same as causation.”
He added: “I’m sceptical that use of hearing aids can be considered to prevent dementia. It seems more plausible to me that the association reflects that individuals on their way to developing dementia struggle to take up or use hearing aids.
“But hearing aids are important in reducing isolation and increasing quality of life, so we should encourage their use anyway.”
