We’ve known that hearing loss is strongly linked to neurodegenerative diseases, such as Alzheimer’s. What has been unclear is whether it is a symptom, cause, or just common comorbidity. A new study out of John Hopkins University has determined that wearing a hearing aid can reduce mental decline by almost half in people at risk of dementia.

Experts estimate that up to 8% of dementia cases could be prevented by stopping hearing loss. 

“As everyone lives longer, the number of people with dementia over time are going up,” said co-principal investigator of the study, Dr. Frank Lin, professor at Johns Hopkins University School of Medicine and the Bloomberg School of Public Health, “These results provide compelling evidence that treating hearing loss is a powerful tool to protect cognitive function in later life, and possibly, over the long term, delay a dementia diagnosis. But any cognitive benefits of treating age-related hearing loss are likely to vary depending on an individual’s risk of cognitive decline.”

The researchers looked at more than 3,000 people from two populations: healthy community volunteers and older adults from the Atherosclerosis Risk in Communities (ARIC) study, a longstanding observational study of cardiovascular health. Participants were between the ages of 70 and 84 and were asked to carry out tests of executive function, language, and memory completed at the start of the study and then three years later.

Participants were randomly assigned to either a control group that received counseling in chronic disease prevention or an intervention group that received treatment from an audiologist and hearing aids, according to the study. Researchers followed up with the groups every six months for three years. At the completion of the study, they were given a score from a comprehensive neurocognitive test.

In the total group, hearing aids did not appear to reduce cognitive decline, the study said. The minor change in the total population could be because the healthy, less at-risk participants weren’t seeing a cognitive decline much at all, which meant the hearing aids couldn’t do much to slow it down.

“We can’t slow down something that’s already really not changing,” Lin said.

But when researchers looked at just the older group at higher risk, they found a significant reduction in cognitive decline, calling into question whether governments and individuals should prioritize hearing health to reduce dementia risk, Lin explained.

In fact, those who were most at risk of cognitive decline through lower education and income, higher rates of diabetes and high blood pressure, or who lived alone saw 48% less cognitive decline if they wore a hearing aid. Experts said the findings added further evidence to the importance of keeping the brain active.

Everyone’s hearing declines with age, Lin said. But why does that increase the risk of dementia?

Researchers think there may be three mechanisms at play:

1) The Cochlea wears out over time. Lin said that the inner ear may send garbled signals to the brain, which has to work harder to redistribute brain power to understand what it’s hearing.

“That’s why people always say it sounds like people are mumbling at me,” he added.

2) Hearing loss may have structural impacts on the brain’s integrity, and parts may be atrophying or shrinking faster — and that is not good for the brain, Lin said.

3) If you can’t hear very well, you might be less likely to go out and participate in social activities.

“We’ve long known that … staying really engaged in commonly social activities is very important for maintaining our cognitive health as well,” Lin noted.

If you’re unsure about your hearing, it’s important to get it checked out NOW, before things start to deteriorate. It would help if you used an aid even with mild hearing loss, according to Dr. Benjamin Tan, Dean’s Fellow at the Yong Loo Lin School of Medicine at the National University of Singapore. 

“It is a simple, effective and practically risk-free method to preserve your cognition as much as possible,” he added.

That said, Tan said that not everyone in the United States has access to regular consultation and treatment with an ear, nose, and throat doctor or an audiologist. In those cases, lower cost over-the-counter hearing aids — available without a prescription — may be a good option.

“Even though you will not have experts diagnosing the cause of your hearing loss or fine-tuning your device, it is probably still better to use a hearing aid than none at all,” he said.

The study also showed the importance of maintaining physical health to prevent cognitive decline. That means checking in with a primary care provider regularly, getting regular physical activity, prioritizing eating leafy greens, berries, and omega-type fatty acids, getting good sleep, and keeping your brain sharp by learning new things.

With cognitive decline and dementia, getting ahead of the problem is the only option. There are no treatments around that can restore cognitive function once it slips away.

If you or someone you know is aging or showing signs for cognitive decline, take action NOW! Don’t wait for things to get worse. Every intervention is a worthwhile one, especially when it’s as simple as a hearing aid!

Sources:
https://pubmed.ncbi.nlm.nih.gov/37478886/
https://www.thelancet.com/journals/lanpub/article/PIIS2468-2667(23)00048-8/fulltext
https://www.nhlbi.nih.gov/science/atherosclerosis-risk-communities-aric-study