Turning up the volume on brain health

Is there a connection between hearing loss and dementia? Researchers have been working intently to answer this question in recent years.

"There are several studies that show an association between hearing loss and cognitive decline," says Dr. Elliott Kozin, assistant professor of otolaryngology–head and neck surgery at Harvard Medical School.

But while the two seem to be linked, doctors say it's too early to say whether hearing loss is actually causing cognitive decline.

"As the statistics mantra goes, 'association is not the same as causation,'" says Dr. Kozin, who specializes in the evaluation and treatment of complex ear disorders at Massachusetts Eye and Ear. "There may be additional or multiple unknown risk factors linked to both hearing loss and cognitive decline." One of those factors may be causing both problems.

However, even though a connection hasn't been confirmed, it's important to get tested if you notice signs that your hearing may not be as sensitive as it used to be. There is already ample evidence that hearing difficulties take a toll on your social ties and your quality of life. Simple solutions can help.

Exploring the link

There are some potential reasons why hearing loss and brain changes may be related.

First, when you can't hear well, you may not be able to communicate well with others, which may affect your social life. This loss of interaction may reduce your quality of life and affect your cognitive processing, says Dr. Kozin.

"Collectively, these problems are theorized to result in the development of conditions like depression or dementia," he says.

It's also possible that hearing loss somehow affects the actual structure of the brain, he says. This, in turn, could make the brain more susceptible to the type of damage that is commonly found in people who have Alzheimer's disease.

A modifiable risk factor?

This potential link between hearing loss and changes in the brain has piqued researchers' interest for two reasons.

First, dementia is a growing concern because the U.S. population is aging, and there is a push to identify modifiable risk factors.

"The thought is that if we identify factors that lead to a condition, such as dementia, we can act early to prevent it, slow it, and potentially even treat it," says Dr. Kozin. If hearing loss causes changes in the brain, for example, it's possible that fitting someone with a hearing aid might head off cognitive deficits.

"This is an active area of research and is being heavily supported by the National Institutes of Health," says Dr. Kozin. "What is generally needed are high-quality prospective longitudinal studies that compare two groups, those with and without hearing loss, to determine if they develop disorders like dementia. As part of these studies, individuals may be given hearing aids to determine if they mitigate risk of conditions like dementia. These studies are challenging; they require large numbers of patients who are closely followed over a period of time."

Second, if hearing loss is an indicator of dementia, it may help doctors to spot the condition earlier. The hope is that it could one day be used as a way to help diagnose dementia, says Dr. Kozin.

It's far too soon to say whether either of these is true, but researchers hope they will someday have an answer.

Understanding hearing loss

In the meantime, Dr. Kozin says people should be alert to hearing deficits. Hearing loss is a common problem among American adults between the ages of 29 and 69, according to a 2017 JAMA study.

"An epidemiologic study supported by the National Institutes of Health indicated that 14% of adults experience hearing loss," says Dr. Kozin. While men are twice as likely as women to have difficulty hearing, women are not immune.

The problem becomes more common with age. "Among adults ages 50 to 59 and 60 to 69, the study found that 23% and 39% of adults had hearing loss, respectively," says Dr. Kozin. But it isn't limited to older adults.

"There is no definite age that one may develop hearing loss, as it could be due to many different factors, such as noise exposure and genetics," says Dr. Kozin. Eight percent of adults in their 40s reported hearing problems, according to the 2017 JAMA study.

Diagnosing the problem

Many people who have hearing deficits aren't aware of the problem.

"Auditory dysfunction results in many different symptoms, such as hearing loss, tinnitus [ringing in the ear], and noise sensitivity. Some individuals may only notice hearing difficulties in noisy environments, such as restaurants," says Dr. Kozin. Other individuals may only be aware due to feedback from friends and family.

While there are no national recommendations that call for hearing screening or testing at certain ages or intervals, get tested if you start experiencing symptoms of hearing loss or if someone points out that you seem to be having difficulty.

"A hearing test is quick and noninvasive. There are many potential treatment options for hearing loss, so testing by a hearing professional may provide actionable next steps," says Dr. Kozin.

Addressing the problem is crucial to healthy aging.

"If hearing rehabilitation also addresses cognitive decline, then this would be a 'bonus' benefit; however, the research does not yet support this direct gain, and clinicians should be wary of making these types of claims to patients," says Dr. Kozin.

While the focus of many health initiatives is often on things like heart health, maintaining the health of your ears is also important.

"We should also be speaking about 'hearing health,' in terms of both hearing loss prevention and treatment. It is well studied that addressing hearing loss will lead to numerous downstream health benefits," says Dr. Kozin. "For this reason, we always recommend hearing protection in noisy environments and some form of hearing rehabilitation strategy if someone has hearing loss."

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