Everything You Need to Know About Hearing Loss and Cognitive Decline
According to Uchida et. al., adults with hearing loss develop significant cognitive impairments 3.2 years sooner than those with normal hearing. To understand how this happens, let’s explore two theories about how hearing loss affects cognitive decline—The Cascade Hypothesis and the Cognitive Load Theory.
The Cascade Hypothesis states that a lack of sensory input, including sound, directly affects brain structure. Though we hear with our ears, we understand with our brain. Therefore, if our ears are not functioning properly, they cannot effectively activate or stimulate the brain. Just like a muscle, the brain will start to atrophy the less it is used. According to Lin, et al., researchers found that brain atrophy leads to a size decrease of the auditory cortex and is directly associated with hearing loss.
The diagram below shows that hearing loss can lead to other problems.
- The first effect of hearing loss is a decrease in social engagement. The less a person hears, the less he can effectively contribute to conversation. Eventually, the lack of interaction will lead to depression, anxiety, and social isolation.
- The second effect is neurological. Since the brain is no longer receiving stimulation from sound, it begins to weaken and atrophy, leading to cognitive impairments such as Alzheimer’s.
- Audiologists play a large role in breaking both cycles through the use of amplification. Amplification devices such as hearing aids can restore auditory input, allowing the brain to once again hear and react to sound.
Cognitive Load Theory
According to Uchida et. al., Cognitive Load Theory states that our brains have a limited number of resources to distribute to functions within the body.
People with normal hearing can balance the resources in their brain, using them to both hear (auditory processing) and remember what was said (memory). However, people with hearing loss cannot balance these functions. Instead, their brains’ resources choose to focus on the area they’re struggling with—hearing, or auditory processing. This imbalance of cognitive resources causes other brain processes, including memory, to not function at full potential.
Imagine you are at a loud, busy restaurant when someone asks you to go get your coat, pay the bill, and start the car. A person with normal hearing would have no problem understanding the directive (auditory processing) as well as remembering to complete all three tasks (working memory). However, if a person with hearing loss were asked to complete the same tasks, he may lean in, tilt his head, and ask for the sentence to be repeated. The person’s hearing loss has caused his brain to work harder to process sounds and has left his memory with too few resources to function properly.
Is Hearing Loss Serious?
Untreated hearing loss deprives the brain of important sound stimuli and has been linked to irreversible brain deterioration. Treating hearing loss quickly is important. The longer you deprive your brain of the sounds found in speech, the harder it will be for your brain to understand them even if they are restored through amplification.
During a hearing evaluation, we ask our patients to repeat a list of words back to us at a comfortable speaking level. I asked one patient to repeat 50 words in her right ear and another 50 words in her left. At the end of the test, she scored 67% in the right ear and 100% in the left ear. The results, known as her Word Recognition Score, showed me that although she could hear me, her brain was not understanding 33% of the words that I said into her right ear. She had been living with unilateral hearing loss for several years. Even after she was fitted with hearing aids, she still could not understand the sounds her brain was receiving from her right ear. If she had been fitted with amplification sooner, preferably right after she noticed hearing loss, she would have saved her brain from permanent damage.
How to Prevent Brain Damage Caused by Hearing Loss
Follow the three suggestions below to maintain your hearing and prevent permanent brain damage.
- Have your hearing routinely checked. Yearly or bi-yearly hearing evaluations are always recommended. Just as you go to the dentist regularly to get your teeth cleaned, you should also have your hearing evaluated.
- Use amplification when needed. If you have hearing loss that can be treated by using amplification, you should be fitted with hearing aids before your hearing loss becomes a serious problem.
- Take care of your ears and hearing devices. Stay away from loud situations that might damage your hearing. Also, if you are fitted with hearing aids, make sure to care for them properly. Hearing aids can last you a long time if they are taken care of by an honest healthcare professional. Ask us about our aural rehabilitative options as well.
Let Us Help
These emotions—frustration, anger, and depression—are typical of a person suffering from hearing loss. If you are experiencing these emotions tied to an inability to hear or understand sound, don’t waste time. Contact Hearing Resources today and we’ll help you restore your hearing and stop cognitive decline.
Uchida, Y., Sugiura, S., Nishita, Y., Saji, N., Sone, M., & Ueda, H. (2019). Age-related hearing loss and cognitive decline — The potential mechanisms linking the two. Auris Nasus Larynx, 46(1), 1–9. doi: 10.1016/j.anl.2018.08.010
Dawes, P., Emsley, R., Cruickshanks, K. J., Moore, D. R., Fortnum, H., Edmondson-Jones, M., … Munro, K. J. (2015). Hearing Loss and Cognition: The Role of Hearing Aids, Social Isolation and Depression. Plos One, 10(3). doi: 10.1371/journal.pone.0119616
Lin, F., Ferrucci, L., An, Y., Goh, J., Doshi, J., Metter, E., … Resnick, S. (2014). Association of hearing impairment with brain volume changes in older adults. NeuroImage, 90, 84–92. doi: 10.1016/j.neuroimage.2013.12.059