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Hearing aids may be key to slowing cognitive decline

Delaying cognitive decline and improving brain function in older adults with the use of hearing aids has been the focus of new research.

Cognitive decline is associated with hearing loss, which affects about 32 per cent of people aged over 55 years, and more than 70 per cent of people aged over 70 years. Hearing loss has been identified as a modifiable risk factor for dementia.

The study, conducted by the University of Melbourne, tested the use of hearing aids in almost 100 adults aged 62–82 with hearing loss.

Participants were assessed before and 18 months after, having hearing aids fitted to test their hearing, cognitive function, speech perception, quality of life, physical activity, loneliness, mood and medical health.

“After 18 months of hearing aid use, we found that speech perception, self reported listening disability and quality of life had significantly improved for participants,” said Associate Professor Julia Sarant, chief investigator leading the study.

“Notably, of a subset of those 100 people who were assessed, over 95 per cent showed either clinically significant improvement or stability in executive function – their mental ability to plan, organise information and initiate tasks.

“This was a very pleasant and unexpected surprise for us, as an improvement in cognitive decline in adults is not something that we normally see,” Sarant said. “I had actually expected to see stability in this group, but definitely not improvement.”

Women, in particular, showed significant improvements in working memory – used for reasoning and decision-making – as well as most other cognitive functions assessed.

The study also found more frequent use of hearing aids was associated with greater improvements in cognitive function, and women were much more diligent at wearing the devices than men.

“Although there are successful treatments for hearing loss, there is currently no successful treatment for cognitive decline or dementia,” Sarant said.

She said that older people generally lose about two decibels of hearing per year and referred to previous research from the Lancet Commission in 2017, showing that hearing loss is accountable for 9 per cent of the modifiable risk factors for dementia.

“While we don’t really totally understand the link between hearing loss and dementia, with regards to increased listening demands for someone with a loss, it has been seen that the brain does not just use the auditory cortex (which we are supposed to use), but also other parts of the brain to assist with comprehension, sound and speech. And this may take away the brain’s ability to deal with other cognitive functions. Basically, they may be having to use more of their brain to listen.

“We also know that someone with a mild hearing loss has double the risk of developing dementia; someone with a moderate loss has almost three times the risk of developing dementia and someone with a severe hearing loss has almost five times the risk. All the evidence points to the fact that if you have an untreated hearing loss you will unfortunately see a faster speed of cognitive decline.”

Sarant acknowledged that there are barriers to hearing aid use which are sometimes seen in settings such as aged care.

“Within aged care homes there are obviously a lot of people with hearing issues, and the onus cannot always be placed on residents to manage their hearing aids with regards to remembering batteries, finding the aids, setting them up, etc. Therefore it does require effort by staff to help manage the use of them.”

Sarant said the latest research is a positive step in investigating the treatment of hearing aids to delay cognitive decline, but that further research is needed.

“Further studies are underway to compare cognitive outcomes from a larger sample size with those of a healthy ageing comparison group of older Australians with typical hearing for their age,” she said.

The study is published in the Journal of Clinical Medicine.

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