Hearing Loss and Cognitive Decline: The Studies

abstract graphic of brain

In 2013, Johns Hopkins University researcher and epidemiologist Dr. Frank Lin directed a study which was the first to analyze the possible impact of hearing loss on mental performance.

Volunteers with hearing loss took repeated cognitive examinations, used to assess memory and thinking skills, over the length of six years. Hearing tests were also carried out over the same period.

What the researchers found was concerning: the cognitive abilities of those with hearing loss diminished 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 people with hearing loss experience higher rates of cognitive decline—the decline was directly connected to the seriousness of the hearing loss. The more intense the hearing loss, the greater deterioration to brain function. Furthermore, those with hearing loss presented signs of significant cognitive deterioration 3.2 years earlier than those with normal hearing.

The research reveals a strong association between hearing loss and cognitive decline, but the question remains as to how hearing loss can generate cognitive decline.

How Hearing Loss Causes Cognitive Decline

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

  1. Hearing loss can result in social isolation, which is a well-known risk factor for cognitive decline.
  2. Hearing loss causes the brain to invest too many resources to the processing of sound, at the expense of memory and thinking.
  3. A common underlying trauma to the brain causes both hearing loss and declined brain function.

Possibly it’s a mixture of all three. What is clear is that, irrespective of the cause, the link between hearing loss and cognitive decline is powerful.

The question now becomes, what can we do about it? Experts estimate that 27 million Americans over age 50, among them two-thirds of men and women aged 70 years and older, experience some kind of hearing loss. Is there a way those with hearing loss can protect against or slow cognitive decline?

How Hearing Aids Could Help

Recall the three ways that hearing loss is thought to trigger more rapid cognitive decline. Now, consider how hearing aids could deal with or correct those causes:

  1. People that use hearing aids gain back their social confidence, become more socially active, and the consequences of social isolation—and its contribution to mental decline—are lessened or eliminated.
  2. Hearing aids prevent the fatiguing effect of struggling to hear. Cognitive resources are freed up for memory and thinking.
  3. Hearing aids produce heightened sound stimulation to the brain, helping to re-create neural connections.

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

The answer could be discovered in a forthcoming study by Dr. Frank Lin, the head researcher of the initial study. Lin is presently working on the first clinical trial to examine whether hearing aids can be objectively measured to prevent or minimize brain decline.

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

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