Treating Hearing Loss May Benefit Brain Health

Hearing loss can be frustrating and stressful. It can also have long-term health effects, including a higher risk of dementia.

Research by Frank Lin, M.D., of the Johns Hopkins University School of Medicine and Bloomberg School of Public Health, has shown a direct relationship between the severity of hearing loss and the risk of dementia. He also led research showing that dementia progresses faster in people with hearing loss.

​​Can treating hearing loss with hearing aids lower the risk or slow the progression of dementia? That crucial question has implications for millions of Americans and their families. About ​1​ in ​3​ U.S. adults ages 65 to 74 have hearing loss. Among people older than 75, that number rises to ​1​ in ​2, according to the National Institutes of Health.

Two recent studies suggest hearing aids may make a difference. In the first large-scale, randomized controlled trial on the use of hearing aids and brain function, known as ​​ACHIEVE for Aging and Cognitive Health Evaluation in Elders, Lin and colleagues tracked nearly 1,000 adults ages 70 to 84 with hearing loss. Half the group received hearing aids; the other half received advice on healthy aging. For three years, all participants were tested regularly on their thinking and memory, as reported in 2023 in The Lancet.

A closer look

The results of ACHIEVE appeared to be disappointing at first glance, Lin said in a talk at the NIH in Bethesda, Maryland, in November 2023. In analyzing the data from the group as a whole, researchers found that the use of hearing aids did not slow down cognitive decline during the three-year study.

But breaking down the data told a different story. “We recruited … from two distinct study populations,” Lin said​, a​​nd the​ two groups had dramatically different outcomes.

About three-quarters of participants were volunteers who had responded to ads for a new study on healthy aging. For this group, the use of hearing aids didn’t make a measurable difference. ​T​hese participants were exceptionally healthy — with lower-than-average dementia risk. During the study, their cognitive decline was minimal and progressed at a snail’s pace. It’s hard to “slow down something that’s already going down very, very slowly — at least within three years,” Lin said.

The second group in the study was recruited from a long-running heart-health study called ​​ARIC for Atherosclerosis Risk in Communities, which was drawn from a random sample of U.S. adults. For this group, which was older and had more dementia risk factors than the healthy​ ​volunteer group, the use of hearing aids slashed the speed of cognitive decline by 48 percent compared with a control group. Given that this group was a random sample of adults, these results are promising for the general population. 

“There are plenty of 75-year-olds with untreated hearing loss,” Lin said. The possibility that hearing aids, which are very safe, could lower their risk of cognitive decline “is incredibly appealing.”

No cognitive losses with hearing aids

Halfway around the globe, audiologist Julia Sarant and her team at the University of Melbourne in Australia have been studying a group of women and men 60 and older with hearing loss. Participants in the study, called ​​ENHANCE for Evaluation of Hearing Aids and Cognitive Effects, were fitted with hearing aids. Every 18 months, they took mental skills tests and had their hearing assessed. A group of older adults (with and without hearing loss) who don’t use hearing aids served as a control group.

At the ​three​-year mark, only 54 of the original 160 hearing-aid participants had completed the two scheduled follow-up assessments, due in large part to lockdowns during the C​OVID​-19 pandemic. But the results from this subset were remarkable. The hearing​ ​aid group remained cognitively stable, according to Sarant’s 2024 report in Frontiers in Aging Neuroscience. By comparison, the cognitive performance of the control group dropped significantly.

ENHANCE and ACHIEVE had different designs and findings, but both studies suggest that hearing aid use may delay cognitive decline, Sarant says. She emphasized that these are still early days. “Given the ​long time course​ of cognitive decline, we need much longer follow-up of people in these studies and others,” she wrote in an email. Researchers will continue to track ACHIEVE participants — those in the control group will have an opportunity to get hearing aids — and the ENHANCE study will continue.

Social and emotional improvements

​​​Though the studies were focused on cognitive abilities, such as working memory and attention, there were other positive outcomes. Participants in the ACHIEVE study who wore hearing aids reported that their ability to communicate improved and they had less loneliness and more social engagement. Participants in an earlier, similar study by Sarant reported improved communication and a better quality of li​​​​fe.

The bottom line? “Looking after your hearing health is also looking after your brain health,” Sarant said via email. “If you want to enjoy quality of life for as long as possible, both in terms of your ability to communicate with the people you care about [and] maintaining your cognitive function, my advice is to have your hearing tested regularly and to use hearing aids consistently when advised to do so.”

(Note: The ENHANCE study was funded in part by a research grant from hearing aid maker Sonova.)