In 2013, Johns Hopkins University researcher and epidemiologist Dr. Frank Lin led a study that was the first to analyze the possible consequence of hearing loss on cognitive function.
Participants with hearing loss took recurring cognitive assessments, used to assess memory and thinking skills, over the span of six years. Hearing tests were also carried out over the same time period.
What the researchers found was concerning: those with hearing loss had cognitive abilities that decreased 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 linked to the severity of the hearing loss. The more severe the hearing loss, the greater impairment to brain performance. In addition, those with hearing loss exhibited signals of appreciable cognitive deterioration 3.2 years sooner than those with normal hearing.
The research shows 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 Produces Cognitive Decline
Researchers have proposed three explanations for the connection between hearing loss and cognitive decline:
- Hearing loss can bring about social isolation, which is a well-known risk factor for cognitive decline.
- Hearing loss forces the brain to commit too many resources to the processing of sound, at the expense of short term memory and thinking.
- A common underlying injury to the brain causes both hearing loss and decreased brain function.
Perhaps it’s a collection of all three. What is apparent is that, irrespective of the cause, the relationship between hearing loss and cognitive decline is powerful.
The concern now becomes, what can be done about it? Researchers estimate that 27 million Americans over age 50, including two-thirds of men and women aged 70 years and older, experience some type of hearing loss. Is there a way those with hearing loss can prevent or overturn cognitive decline?
How Hearing Aids Could Help
Remember the three ways that hearing loss is thought to cause accelerated cognitive decline. Now, think about how hearing aids could address or correct those causes:
- People that use hearing aids gain back their social confidence, become more socially active, and the side effects of social isolation—and its contribution to mental decline—are lessened or removed.
- Hearing aids prevent the fatiguing effect of struggling to hear. Mental resources are freed up for memory and thinking.
- Hearing aids produce heightened sound stimulation to the brain, helping to re-establish neural connections.
Admittedly, this is only theoretical, and the big question is: does using hearing aids, in fact, slow or prevent accelerated mental decline, and can we measure this?
The answer could be found in an 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 protect against or mitigate brain decline.
Stay tuned for the results of this research, which we’ll cover on our blog once published.