In 2013, Johns Hopkins University researcher and epidemiologist Dr. Frank Lin led a study that was the first to measure the possible consequence of hearing loss on cognitive function.
Research volunteers with hearing loss took repeated cognitive assessments, used to assess memory and thinking skills, over the course of six years. Hearing tests were also conducted over the same period.
What the investigators discovered 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 age, high blood pressure, and diabetes.
But that wasn’t everything. Not only did those with hearing loss suffer from higher rates of cognitive decline—the decline was directly connected to the severity of the hearing loss. The more serious the hearing loss, the greater impairment to brain functioning. Furthermore, those with hearing loss showed signs of significant cognitive deterioration 3.2 years sooner than those with average hearing.
The research depicts 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 Causes Cognitive Decline
Researchers have offered three reasons for the connection between hearing loss and cognitive decline:
- Hearing loss can contribute to social isolation, which is a recognized risk factor for cognitive decline.
- Hearing loss forces the brain to invest 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 diminished brain function.
Perhaps it’s a blend of all three. What is evident is that, regardless of the cause, the connection between hearing loss and cognitive decline is powerful.
The question now becomes, what can we do 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 overturn cognitive decline?
How Hearing Aids Could Help
Recall the three ways that hearing loss is thought to trigger more rapid cognitive decline. Now, contemplate how hearing aids could resolve or correct those causes:
- Individuals with hearing aids restore their social confidence, become more socially active, and the consequences of social isolation—and its contribution to brain decline—are mitigated or eliminated.
- Hearing aids protect against the overtaxing impact of struggling to hear. Cognitive resources are freed up for memory and thinking.
- Hearing aids yield amplified sound stimulation to the brain, helping to re-establish neural connections.
Admittedly, this is mainly theoretical, and the big question is: does wearing hearing aids, in fact, slow or prevent hastened mental decline, and can we quantify this?
The answer could 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 of this study, which we’ll cover on our blog once published.