In 2013, Johns Hopkins University researcher and epidemiologist Dr. Frank Lin led a study that was the first to appraise the possible impact of hearing loss on cognitive performance.
Research volunteers with hearing loss took recurring cognitive assessments, used to evaluate memory and thinking skills, over the length of six years. Hearing tests were also performed 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 everything. Not only did those with hearing loss experience higher rates of cognitive decline—the decline was directly linked to the severity of the hearing loss. The more intense the hearing loss, the greater impairment to brain performance. Moreover, those with hearing loss displayed signals of appreciable cognitive deterioration 3.2 years earlier than those with normal hearing.
The research shows a strong association between hearing loss and cognitive decline, but the question persists as to how hearing loss can generate cognitive decline.
How Hearing Loss Produces Cognitive Decline
Researchers have suggested three reasons for the connection between hearing loss and cognitive decline:
- Hearing loss can lead to social isolation, which is a recognized risk factor for cognitive decline.
- Hearing loss forces the brain to allocate too many resources to the processing of sound, at the expense of memory and thinking.
- A common underlying trauma to the brain causes both hearing loss and reduced brain function.
Perhaps it’s a mixture of all three. What is clear is that, regardless of the cause, the relationship between hearing loss and cognitive decline is powerful.
The concern now becomes, what can we do about it? Researchers estimate that 27 million Americans over age 50, among them two-thirds of men and women aged 70 years and older, suffer from some kind of hearing loss. Is there a way those with hearing loss can prevent or counter cognitive decline?
How Hearing Aids Could Help
Recall the three ways that hearing loss is considered to cause accelerated cognitive decline. Now, contemplate how hearing aids could deal with or correct those causes:
- Individuals with hearing aids increase their social confidence, become more socially active, and the problems of social isolation—and its contribution to brain decline—are mitigated or removed.
- Hearing aids protect against the fatiguing effect of struggling to hear. Mental resources are freed up and available for memory and thinking.
- Hearing aids present elevated sound stimulation to the brain, helping to re-create neural connections.
Admittedly, this is only theoretical, and the big question is: does using hearing aids, in fact, slow or protect against hastened mental decline, and can we measure this?
The answer may be discovered in an upcoming study by Dr. Frank Lin, the head researcher of the initial study. Lin is working on the first clinical trial to examine whether hearing aids can be objectively measured to protect against or alleviate brain decline.
Stay tuned for the results, which we’ll cover on our blog once published.