You might think hearing loss is something that happens late in life, but about 30% of men and 20% of women start experiencing issues with hearing by the time they're 40.
Blame it on loud concerts or cranking up the music on headphones all those years, but adults start losing their hearing so gradually that they aren't aware of it. By the time they realize they have a problem, some age-related cognitive decline may have occurred.
A study published in the Journal of the American Geriatrics Society says that fixing the audio issue with hearing aids can help put the brakes on memory loss, slowing the rate of dementia and mental decline.
"We found the rate of cognitive decline was slowed by 75 percent following the adoption of hearing aids," study author Asri Maharani, a researcher at the University of Manchester in the division of neuroscience and experimental psychology, tells NPR. "It is a surprising result."
To measure cognitive ability, researchers performed simple tests with participants every two years for nearly two decades. In one test, for example, they were read a list of 10 simple nouns and then were asked to repeat them immediately afterwards and then again after a short time had passed. The researchers calculated an episodic memory score by adding the number of words recalled immediately and the number remembered after the delay.
During the study, the researchers charted when and if each volunteer began using hearing aids. They found that although episodic memory declined significantly with age, the rate of decline was slower after participants began using hearing aids.
It makes sense, audiologist Dina Rollins tells NPR. "Stimulating your ears stimulates the nerves that stimulate your brain." she says. "We're giving your ears back what they're missing, and giving your brain what it needs to make sense of what you're hearing."
A more recent study also found that among people with hearing loss, those who used hearing aids had lower rates of dementia, depression and fall-related injuries compared to those who didn't use the devices. The researchers studied 114,862 adults, aged 66 years and older, who were diagnosed with hearing loss. The results were also published in the Journal of the American Geriatrics Society.
“Prevalence of hearing loss is estimated to increase as our population grows older, and we know there are strong associations between uncorrected hearing loss and conditions such as Alzheimer’s disease or dementia,” lead author Dr. Elham Mahmoudi of the University of Michigan in Ann Arbor told Reuters Health.
The first team of researchers did a similar study looking at whether correcting vision problems (specifically cataracts) could have a similar impact on arresting cognitive decline. According to the National Eye Institute, people can often have cataracts in their 40s and 50s, but they typically don't begin to affect vision until their 60s or later.
Visual impairment has long been linked with lower mental ability, so the researchers looked at the mental abilities of more than 2,000 patients who had cataract surgery.
In that study, which was published in the journal PLOS One, they found the rate of cognitive decline was slowed significantly after surgery. It didn't turn back the clock, but it at least slowed down the rate of mental decline.
"Cataract surgery may have a positive impact on trajectories of cognitive decline in later life," the researchers concluded. "Further research is required to identify the mechanism to explain the association between cataract surgery and cognitive ageing, and whether early intervention towards vision correction results in a reduction in dementia risk."
As researchers continue to study healthy aging, this look into the role of hearing and visions is just one more piece to the cognitive puzzle.
Editor's note: This story has been updated with new information since it was written in October 2018.