The Effect of Hearing Loss on the Brain
Hearing disability is an important issue in geriatric medicine, because it is associated with additional health issues, including accelerated cognitive decline, depression, increased risk of dementia, poorer balance, falls, hospitalizations, and early mortality.
To answer our questions about hearing loss, Consultant360 reached out to Rebecca Sherman, AuD, who is an audiologist with ENT and Allergy Associates in Manhattan, New York.
Consultant360: How does hearing loss affect the brain?
Rebecca Sherman, AuD: There are a few theories as to why hearing loss affects the aging brain. Firstly, hearing loss may lead to a higher cognitive load. When hearing loss is present, the brain must “reallocate” resources to process auditory information, which results in greater difficulty for the brain to perform its regular functions. Studies suggest hearing loss may also lead to structural changes in the brain, as well as a higher atrophy rate.1-3 As with most other anatomy, this change in structure leads to a change in function.
Hearing loss has also been linked to social isolation.2,3 Individuals are more likely to pull away from their regular activities and social commitments when they have hearing loss and struggle to understand those around them. Social isolation and dementia have been found to be closely tied—social isolation can increase the risk of dementia and cognitive decline.
C360: Sensory abilities decline with age. What is the link between untreated hearing loss and dementia?
Dr Sherman: One study conducted by Frank Lin, MD, PhD, from the Johns Hopkins University School of Medicine2 observed that untreated hearing loss resulted in up to a 5-fold higher risk of dementia. Those with mild untreated hearing loss had double the risk of developing dementia, those with moderate hearing loss had triple the risk, and those with severe hearing loss had 5 times the risk, compared with their normal-hearing peers. This heightened risk was still present even when diabetes, blood pressure, age, sex, and race were considered.
C360: The onset of hearing loss is subtle, and consequently, delays in recognizing and seeking help for hearing difficulties are common. In what ways is hearing loss gradual and why?
Dr Sherman: Age-related hearing loss occurs slowly over time.2 Many patients are surprised to learn they have significant loss, as they do not notice many hearing challenges. It appears that because hearing loss is gradual, patients do not realize all the auditory information that they’re missing—they may have adjusted to the loss over time. However, many of these patients realize the severity of their loss once they try on hearing aids. Patients will often return after their initial hearing aid fitting and report all the sounds they have realized they have been missing. Examples include the refrigerator humming, computer keys typing, and the clicking of a car’s turn signal. Individuals will typically realize they are no longer straining to understand conversations, even if they did not realize they were having difficulty prior to obtaining hearing aids.
C360: What is the overall importance of monitoring hearing as patients get older?
Dr Sherman: Because of the myriad of health risks associated with hearing loss in the older adult population, it is crucial to monitor hearing and begin intervention as soon as hearing loss is identified. The risks of untreated hearing loss along with the low percentage of individuals with hearing loss that pursue hearing aids, results in a major public health problem. We have the technology (hearing aids) to reduce this unnecessary extra layer of risk for dementia, but many individuals are unaware of this problem and thus are not treating their loss.
Additionally, it is better to obtain hearing aids sooner rather than later. The sooner we can begin reducing the cognitive load of the brain and begin properly stimulating the auditory nerve, the more perceived benefit there will be. It also takes the brain time to adjust to hearing aids. Patients typically need to start at an amplification level below their full prescription and have this level slowly increased. Patients often report everything is too loud if they are introduced to their full prescription immediately, which again highlights that patients are often unaware of all the sounds they are missing.
C360: Is there anything else that you would like to add?
Dr Sherman: In the United States, 50% of people aged 75 years or older have disabling hearing loss—28.8 million adults in the United States would benefit from hearing aids.1 However, less than 30% of individuals aged 70 years or older are treating their hearing loss.1 I personally recommend obtaining a baseline hearing test at 50 years of age. If an individual has normal hearing, he or she can monitor his or her hearing every few years or sooner if he or she believes a change has occurred. For those with hearing loss, monitoring should be annually—if the loss does not yet require hearing aids, it also gives the patient time to accept that they will likely need hearing aids at some point in their life. I call this “planting the seed of hearing aids,” so that when the hearing loss worsens and hearing aids are recommended, patients have had time to warm up to the idea and are less hesitant. Although most individuals at 50 years of age will not have significant hearing loss, there are instances where loss is observed and thus aids are recommended.
References:
- Quick statistics about hearing. National Institute on Deafness and Other Communication Disorders. Updated March 25, 2021. Accessed July 8, 2021. https://www.nidcd.nih.gov/health/statistics/quick-statistics-hearing
- Lin FR, Metter EJ, O’Brien RJ, Resnick SM, Zonderman AB, Ferrucci L. Hearing loss and incident dementia. Arch Neurol. 2011;68(2):214-220. https://doi.org/10.1001/archneurol.2010.362
- Lin F. How is hearing loss related to cognitive decline and dementia? Audiologyonline. Published online July 15, 2019. https://www.audiologyonline.com/ask-the-experts/hearing-loss-related-to-cognitive-25114
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