Hearing Loss and Cognitive Decline: The Studies

abstract graphic of brain

In 2013, Johns Hopkins University researcher and epidemiologist Dr. Frank Lin guided a study which was the first to evaluate the possible consequence of hearing loss on cognitive performance.

Participants with hearing loss took recurring cognitive tests, used to quantify memory and thinking skills, over the span of six years. Hearing tests were also conducted over the same time period.

What the researchers found was concerning: those with hearing loss had cognitive abilities that declined 30 to 40 percent faster than those with normal hearing, even after accounting for other contributing factors like high blood pressure, age, and diabetes.

But that wasn’t all. Not only did those with hearing loss experience higher rates of cognitive decline—the decline was directly related to the severity of the hearing loss. The more extreme the hearing loss, the greater deterioration to brain function. Furthermore, those with hearing loss exhibited symptoms of significant cognitive deterioration 3.2 years sooner than those with normal hearing.

The research demonstrates a strong connection between hearing loss and cognitive decline, but the question persists as to how hearing loss can result in cognitive decline.

How Hearing Loss Produces Cognitive Decline

Researchers have offered three explanations for the correlation between hearing loss and cognitive decline:

  1. Hearing loss can bring about social isolation, which is a well-known risk factor for cognitive decline.
  2. Hearing loss forces the brain to dedicate too many resources to the processing of sound, at the expense of memory and thinking.
  3. A shared underlying trauma to the brain causes both hearing loss and diminished brain function.

Possibly it’s a mix of all three. What is evident is that, irrespective of the cause, the link between hearing loss and cognitive decline is strong.

The concern now becomes, what can we do about it? Experts estimate that 27 million Americans over age 50, including two-thirds of men and women aged 70 years and older, suffer from some type of hearing loss. Is there a way those with hearing loss can protect against or overturn cognitive decline?

Can Hearing Aids Help?

Recall the three ways that hearing loss is believed to cause more rapid cognitive decline. Now, think about how hearing aids could deal with or correct those causes:

  1. People with hearing aids boost their social confidence, become more socially active, and the effects of social isolation—and its contribution to mental decline—are mitigated or eliminated.
  2. Hearing aids prevent the fatiguing impact of struggling to hear. Cognitive resources are freed up for memory and thinking.
  3. Hearing aids generate heightened sound stimulation to the brain, helping to re-create neural connections.

Admittedly, this is only theoretical, and the big question is: does wearing hearing aids, in fact, slow or protect against hastened mental decline, and can we quantify this?

The answer could be found in an upcoming study by Dr. Frank Lin, the lead researcher of the initial study. Lin is working on the first clinical trial to study whether hearing aids can be objectively measured to prevent or mitigate brain decline.

Stay tuned for the results of this study, which we’ll cover on our blog once published.

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