In 2013, Johns Hopkins University researcher and epidemiologist Dr. Frank Lin directed a study that was the first to measure the possible consequence of hearing loss on mental function.
Research volunteers with hearing loss took repeated cognitive examinations, used to measure memory and thinking skills, over the length of six years. Hearing tests were also performed over the same time period.
What the investigators discovered was concerning: those with hearing loss had cognitive abilities that 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 everything. Not only did those with hearing loss experience higher rates of cognitive decline—the decline was directly associated to the seriousness of the hearing loss. The more severe the hearing loss, the greater deterioration to brain functioning. Additionally, those with hearing loss exhibited symptoms of appreciable cognitive deterioration 3.2 years earlier than those with average hearing.
The research demonstrates a deep connection between hearing loss and cognitive decline, but the question persists as to how hearing loss can cause cognitive decline.
How Hearing Loss Triggers Cognitive Decline
Researchers have suggested three explanations for the relationship between hearing loss and cognitive decline:
- Hearing loss can lead to social isolation, which is a known risk factor for cognitive decline.
- Hearing loss causes the brain to commit too many resources to the processing of sound, at the expense of short term memory and thinking.
- A common underlying trauma to the brain causes both hearing loss and diminished brain function.
Perhaps it’s a mix of all three. What is apparent is that, regardless of the cause, the relationship between hearing loss and cognitive decline is strong.
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 kind of hearing loss. Is there a way those with hearing loss can prevent or reverse cognitive decline?
How Hearing Aids Could Help
Recall the three ways that hearing loss is thought to trigger accelerated cognitive decline. Now, think about how hearing aids could deal with or correct those causes:
- People that use hearing aids gain back their social confidence, become more socially active, and the consequences of social isolation—and its contribution to cognitive decline—are mitigated or eliminated.
- Hearing aids prevent the overtaxing impact of struggling to hear. Mental resources are freed up for memory and thinking.
- Hearing aids yield boosted sound stimulation to the brain, helping to re-create neural connections.
Admittedly, this is mainly theoretical, and the big question is: does using hearing aids, in fact, slow or protect against hastened mental decline, and can we quantify this?
The answer could be discovered in an forthcoming study by Dr. Frank Lin, the lead researcher of the initial study. Lin is currently 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, which we’ll cover on our blog once published.