Hearing loss is a major risk factor for dementia. Hearing aids can help.
Dementia is one of the main health obstacles to aging well. It’s irreversible, but we can reduce our risk of getting it. An important, and historically underestimated, way to prevent it is to address hearing loss. By taking care of our hearing, we can also take care of our brain.
More than 50 million people were living with dementia worldwide in 2019. This number is expected to increase as the population ages: more than 130 million people are expected to be living with dementia in 2050.
Hearing loss in middle age – ages 45 to 65 – is the strongest risk factor for dementia, accounting for more than 8% of all dementia cases, according to research. A Lancet Report 2020 calculated that hearing loss approximately doubles the risk of dementia, which is similar to the increased risk caused by traumatic brain injury. Additionally, because hearing ability exists on a continuum, even subclinical hearing loss can mean an increased risk of dementia.
Listen up: you can now buy hearing aids without a prescription
As a way to reduce the onset of dementia, hearing loss is a win-win, said Frank Lin, director of the Cochlear Center for Hearing and Public Health at the Johns Hopkins Bloomberg School of Public Health. “It’s really common, it’s treatable, and there are interventions that don’t pose any risk” that are underused, he said.
Preserving our ability to hear is fundamental to “public health strategies that can best optimize the health of the elderly population, so that older people live long and full lives until the very end,” Lin said.
Why impaired hearing can impair cognition
There are several overlapping hypotheses to explain why hearing loss in middle age is associated with a higher risk of dementia.
One hypothesis suggests that poor hearing increases cognitive load on the brain, which has to work harder, at the expense of other mental faculties, to decipher the scrambled signals that the ears send.
However, that may not be the best explanation, as people with hearing loss and cognitive decline also struggle to pass tests that don’t depend on hearing, said Tim Griffithsprofessor of cognitive neurology at the University of Newcastle in England.
Research into the health effects of hearing loss suggests that hearing aids may reduce the risk of dementia
Animal and human research has shown that with hearing loss, the the brain atrophies fasterparticularly in the temporal lobe – where key auditory and memory functions occur – potentially due to reduced use and stimulation.
Hearing loss can also cause aberrant activity in the temporal lobe, making it more susceptible to damage and pathology associated with Alzheimer’s disease, Griffiths said.
Hearing loss can make it difficult to connect with others, leading to social isolation, loneliness and depression, which are known risk factors for dementia. As deaf-blind author and activist Helen Keller once said, “Blindness cuts us off from things, but deafness cuts us off from people.”
How to take care of our ears and brain
The sensory cells of the cochlea in our inner ear allow us to hear. These sensory cells, called hair cells, translate sound wave vibrations striking our eardrums into electrical signals that are sent to the auditory regions of the brain, which decode them into what we perceive as sound.
When these hair cells break down or die, the signals sent to the brain also become scrambled. These hair cells are not regenerated.
Prolonged exposure to loud noise is one of the ways we can permanently damage our cochlear hair cells and, therefore, our hearing. Avoiding loud noises or wearing earplugs in environments where you know you will be subjected to potentially harmful sounds is key to protecting your hearing.
We also lose hearing as we age, a process that is not fully understood.
“It’s not inevitable,” Griffiths said. “There is a population of older people who have no hearing loss.”
But many people will experience choking, which is a gradual loss of hearing, as they age. According to National Institute of Deafness and Other Communication Disorders1 in 3 people between the ages of 65 and 74 and nearly half of people over 75 have clinical hearing loss.
Knowing our own hearing ability, or hearing number, by going to resource websites such as audiencenumber.org is crucial to understanding how we can address any shortfalls, Lin said. Like daily step count, cholesterol level, or weight, “it’s another measure that you know about a dimension of your own health,” he said.
Hearing aids are now sold without a prescription. Here’s how to choose one.
Most people who can benefit from hearing aids do not use them. For hearing-impaired adults aged 70 and over, only 30% report using the devices; for young adults with hearing loss, only 16% use hearing aids.
If you have hearing loss, hearing aids can help and can also preserve your mental abilities. Preliminary studies seem to promise that the use of hearing aids protects against dementia. A review of 30 studies found that although people with hearing loss had lower cognition than those with normal hearing, those who used hearing aids do better cognitively than those without use hearing aids.
Lin leads a large randomized controlled trial with nearly 1,000 older people to answer more definitively whether treating hearing loss with hearing aids reduces the risk of cognitive decline. After three years and $40 million, the trial will end in 2023.
We have a lot of control over how we age. It is believed that around 40% of dementias are potentially preventable by addressing risk factors such as hypertension, sleep problems, alcohol consumption, smoking, social isolation and obesity.
And taking care of our hearing is one of the greatest gifts we can give ourselves, now and in the future.
To reap the benefits of better hearing and preserved cognition, “I think the key is to have properly fitted hearing aids and to wear them,” Griffiths said.
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