Wearing a hearing aid won’t just help you carry out a conversation – it could also delay the onset of dementia.
Researchhas shown there is a link between hearing loss and cognitive decline. The reported risk of developing dementia for people with mild hearing loss is almost double that of a person with normal hearing, while the risk for people with severe hearing loss is almost five times higher.
It’s not just older people who are affected, either. People who develop hearing loss before the age of 50 are also at greater risk of cognitive decline.
This link is significant because there is currently no successful treatment for cognitive decline or dementia, but there are successful treatments for hearing loss.
Now, new research conducted by the University of Melbourne and published in the Journal of Clinical Medicine has shown that hearing aid use might not just help your hearing – it could have a positive impact on your brain, too.
After 18 months of hearing aid use, 97.3 per cent of the people who were followed up in the study showed either clinically significant improvement or stability in executive function – their mental ability to plan, organise information and initiate tasks.
Researchers found speech perception, self-reported listening disability and quality of life had also significantly improved for the participants, who were all adults with hearing loss aged between 62 and 82.
University of Melbourne Associate Professor Julia Sarant, the chief investigator of the study, says there was an “obvious” need to examine the link between hearing aids and cognitive decline.
“We’ve got these two big problems that seem to be connected and that have an enormous cost, both in terms of quality of life and also the cost to society,” she says. “So I thought, well, what would happen to one of these problems if I tried to treat the other?”
“I thought, well, what would happen to one of these problems if I tried to treat the other?”
The World Health Organisation estimates that by 2030, roughly 82 million people worldwide will be living with dementia. That number is expected to increase to 152 million by 2050, tripling the current number.
After 65 years of age, the risk of developing dementia doubles every five years, and 25 to 35 per cent of people aged over 85 years are affected.
While the link between cognitive decline and hearing loss – which affects more than 70 per cent of people aged over 70 years – seems to have been established, there are still major questions to be answered.
“The mechanisms that actually link hearing loss and cognitive decline are still unknown, but there are some theories,” Associate Professor Sarant says.
“One theory is that hearing loss and cognitive decline are both a part of the ‘natural’ neurodegenerative ageing process. As we age, things start not to work as well, across our whole body. The link could be that simple.
“Another theory is that the increased listening demands that come with hearing loss affect cognition. There’s a thing called ‘listening effort’ – the amount of effort your brain has to put into understanding what’s being said to you. Most people would notice this increased listening effort if they were talking in a crowded room, for instance, as opposed to talking in a quiet space.
“Well, people with hearing loss are always required to increase their listening effort. This could affect cognition because it draws more of the brain’s resources into the speech perception process. The brain has to work harder to decipher what’s being said, and that could change the neural wiring of the brain.
“Social factors need to be considered, too. If you’re dealing with hearing loss, it can be embarrassing and difficult for you to communicate with other people, and that leads to social isolation and loneliness. Those things, in turn, can lead to depression, which is a risk factor for dementia.
“Finally, a decrease in brain volume – particularly in the auditory cortex and the hippocampus – has been found in people with hearing loss who have died. Similar brain shrinkage has been found in people with dementia who have died. We don’t know how this all fits together yet – but then, we don’t know exactly what causes dementia, either.”
There is more work to be done. Associate Professor Sarant is currently conducting further research to expand the scope of the study and compare the cognitive outcomes of a larger sample size with a healthy ageing comparison group over a longer period of time, in order to generalise the results for the wider population.
Sarant says that hearing aids could prove to be a very economical way to preserve cognitive function and improve quality of life for older adults.
“Hearing aid use is relatively cost-effective and very safe,” she says. “In 2017-18, the Australian Government spent $18 billion on aged care. If we could delay the onset of dementia for even, say, three years for a moderate number of people, that would still be an enormous cost saving.”
“If we could delay the onset of dementia for even, say, three years… that would still be an enormous cost saving.”
In the meantime, Sarant urges older people with hearing loss to consider using a hearing aid regardless.
“Up to 76 per cent of people who need hearing aids do not have them, and of those who do have them, 24 per cent do not use them,” she says.
“I think a lot of that has to do with the stigma associated with hearing aids. Just like people don’t want to be seen using a walking stick or a wheelie walker, people don’t want to be seen with a hearing aid.
“To me, the take-home message from this study is that if you’re in your 50s or older, you should go and get your hearing tested regularly every couple of years. Because if you do have hearing loss, even if you take dementia out of the equation, using a hearing aid will lead to better communication with the people you love and a better social life.
“And if it can keep your brain sharper, too… well, it’s an absolute no-brainer.”