Hearing aids may reduce your risk of dementia by half, study says

By Madeline Holcombe, CNN

(CNN) — For people facing a greater threat of cognitive decline, getting hearing aids could cut your risk in half, according to a new study.

Cognitive decline is a reduction in abilities that can range from mild impairment to dementia, according to the US Centers for Disease Control and Prevention, and dementia is a big problem across the globe.

“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.

Over the past decade, research has established that hearing loss is one of the biggest risk factors for developing dementia, but it wasn’t clear whether intervening with hearing aids would reduce the risk, he added.

But the study published Tuesday in the Lancet was the first randomized control study to investigate this question, Lin said.

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 randomly assigned to either a control group that received counselling 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, and at the end, 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. But when researchers looked at just the older group that was at higher risk, they found a significant reduction in cognitive decline, Lin said.

“That was very impressive to see that in the unhealthy individuals they were able to slow the rate of cognitive decline by 48%,” said Dr. Thomas Holland, physician scientist at the Rush Institute for Health Aging. Holland was not involved in the study.

The smaller change over the total population could be because if the healthy, less at-risk participants weren’t seeing cognitive decline much at all, then the hearing aids couldn’t do much to slow it down, he added.

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

But the population more at risk saw rates of cognitive decline at levels almost three times higher than their counterparts, and the results call into question whether governments and individuals should prioritize hearing health to reduce dementia risk, he added.

Why hearing loss may increase dementia risk

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

There are three mechanisms researchers think may be at play, he said.

One is that if the cochlea wears out over time, the inner ear may be sending garbled signals to the brain, which has to work harder and redistribute brain power to understand what it’s hearing, Lin said.

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

Another is that 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.

The last possible mechanism is that 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 said.

What to do about it

First things first: If you aren’t sure about your hearing health, get it checked, Lin said.

Even if you have only mild hearing loss, use an aid, said Dr. Benjamin Tan, Dean’s Fellow at the Yong Loo Lin School of Medicine at the National University of Singapore. Tan was not involved in the new study.

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

That said, not everyone in the United States has access to regular consultation and treatment with an ear, nose and throat doctor or an audiologist, Tan said. 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.

But the study also showed the importance of maintaining physical health to prevent cognitive decline.

“What this study is really telling us is that individuals that do have those underlying comorbidities, or risk factors for cognitive decline, need to be even more diligent about doing those annual visits,” Holland said.

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, he added.

Those elements are especially important if you have hearing loss, atherosclerosis, high blood pressure, heart disease or neurovascular disease, Holland said.

With cognitive decline and dementia, it is most effective to get ahead of the problem.

“Intervening earlier to either prevent the disease process altogether or to help build resilience in the face of a disease process is ideal,” he added.

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