Introduction:
This is an often-asked question among professionals and among people with hearing loss.
The answer is variable and is not as straight forward as any of us would like. One of the reasons this question is so difficult is that it may indeed be the wrong question (see below).
Nonetheless, the answer with which I am very comfortable goes like this:
“Untreated hearing loss may exacerbate cognitive decline in at-risk patients/people and the risk appears to increase as hearing loss increases.”
To be clear, hearing is simply detecting or perceiving sound. Listening is comprehending or understanding, or applying meaning to sounds. Listening involves auditory processing, information processing and listening is more-or-less a ‘whole brain’ event. Cognition can be defined as knowing and acquiring knowledge through sensory input (like vision and hearing) experience and thought processes. As such, the distinction between hearing and listening is pivotal in that listening and cognition involve active and intricate brain-based processing, whereas hearing is simply a detection task, requiring almost no processing at all.
Leavitt, Beck and Flexer (2023) noted the more appropriate question might be “Would the correlation between listening and cognition be even greater than those reported for hearing and cognition?” Probably yes. Of note, measuring listening is very difficult and measuring hearing is very easy. As such, the vast literature produced on these topics addresses hearing, not listening. And resultantly, we are perhaps looking at the trees, rather that the forest.
Therefore, as you read through the rest of this article, please keep in mind that the science related to these topics is evolving rapidly, and unfortunately correlations and conclusions as of this writing (October, 2023) are essentially based on hearing (detection), not listening (comprehending).
A brief review of the relationship between hearing loss and cognition
As noted above, untreated hearing loss does appear to increase the risk of cognitive decline. This is not a new observation.
Peters et al (1988) reported cognitive decline was greater in hearing impaired individuals and for people with Alzheimer’s Disease, hearing impairment predicted a more rapid cognitive decline.
Rawool (2007) reported that amplification can compensate for hearing loss and amplification can deliver auditory information to reduce cognitive demand.
Schum & Beck (2009) reported “Negative Synergy” occurs when aging and cognitive decline occur along with hearing loss, which creates an overall worse situation than the individual components might indicate.
Gold and colleagues (1996) reported a high prevalence of hearing loss in individuals with cognitive deficits.
Beck & Clark (2009) wrote that patients live in a world where cognition, attention, memory, and hearing interact and each plays a critical role in listening. They reported that people with hearing loss must dig deep into their cognitive reserve and cognitive abilities to make sense of a world delivered to them via compromised auditory input. They stated “audition matters more as cognitive ability decreases, and cognition matters more as auditory ability decreases.”
Beck & Flexer (2011) wrote “Listening is Where Hearing Meets Brain.” They reported hearing is a sense and listening is a learned skill. They stated listening experiences in infancy are the foundation upon which language and literacy and cognitive and psychological experiences and development occurs.
Edwards (2013) reported there exists increasing evidence that hearing loss can result in cascading cognitive and psycho-social decline as well as increased cognitive load, mental fatigue, poor memory, worse auditory scene analysis, reduced attention, less focus, worse mental health, social withdrawal, and depression. He noted hearing aids may be beneficial as they may improve the quality of the auditory signal impacting the cognitive system.
Lemke (2013) stated that when hearing loss degrades the auditory signal which eventually feeds the cognitive system, this may result in a “cascade of cognitive and psycho-social declines…” Lemke noted that hearing loss negatively affects cognitive ability and amplification may be beneficial in resolving some of these problems.
Lunner (2013) reported that the signal processing used in hearing aids may impact cognitive function and the ability to comprehend speech in positive and negative ways.
Lin (2013) noted that significant hearing loss in older adults was independently associated with poorer cognitive functioning regarding memory, executive function, accelerated cognitive decline and the risk of incident dementia. Lin reported it was unknown (in 2013) whether hearing therapies would be useful to help mitigate cognitive decline or perhaps delay dementia in older adults.
Amieva, Ouvrard, Giulioli and colleagues (2015) studied 3,670 people over a 25-year period with a focus on cognitive screenings, self-perceived hearing loss and hearing aid use. They concluded that those who reported hearing loss generally had lower cognitive screening scores and they declined more rapidly than those who did not report hearing loss. Interestingly, for those with hearing loss who used amplification, there was no difference in cognitive decline from the control group (those with no self-reported hearing loss). The authors stated “Self-reported hearing loss is associated with accelerated cognitive decline in older adults; hearing aid use attenuates such decline.” https://pubmed.ncbi.nlm.nih.gov/26480972/
Although there were many other reports establishing the relationship between hearing loss and cognition, we will turn our attention to 2020-2023 to provide some of the most recent scientific and peer-reviewed information.
Livingston, Huntley, Sommerlad and colleagues (2020) published a ground-breaking article on dementia (https://www.thelancet.com/article/S0140-6736(20)30367-6/fulltext). They reported that some 60% of your risk for dementia was due to aging and deoxyribonucleic acid (DNA) and the other 40% was due to 12 potentially modifiable risk factors. Of the 12, untreated hearing loss was the most significant with an 8.2% population attributable factor (PAF).
Jiang, Mishra, Shrestha (2023) reviewed data from 430 thousand people who participated in the UK Biobank study (https://www.thelancet.com/action/showPdf?pii=S2468-2667%2823%2900048-8). Participants were asked “Do you have any difficulty with your hearing?” and “Do you use a hearing aid most of the time?” There were three groups of responses. 1- No reported hearing difficulties. 2- Hearing difficulties with hearing aid use, and 3- Hearing difficulties without hearing aid use. The authors reported study participants with hearing difficulties who did not use a hearing aid had a higher risk of being diagnosed later with all-cause dementia than those without hearing loss. Participants with hearing difficulties who used a hearing aid did not. They reported “up to 8% of dementia cases could be prevented with proper hearing loss management… our findings highlight the urgent need to take measures to address hearing loss to improve cognitive decline.”
Bottom Line
It appears likely that untreated hearing loss increases the risk of cognitive decline in many people who are at high risk. The risk of cognitive decline varies tremendously based on DNA, age, overall cognitive, emotional, physical health, the above mentioned potentially modifiable risk factors, as well as type and degree of hearing loss and much, much more.
Regarding whether hearing aid fittings slow cognitive decline, and if so, would OTC and prescription hearing aids offer the same benefit? No one knows. There are certainly studies which have found that treating hearing loss with professionally fit hearing aids appears to have a “normalizing effect” (see Amieva, 2015; see Jiang, Mishra and Shrestha 2023), but this did not occur with every single participant. Further, as of yet, there are no peer-reviewed studies regarding OTC and long-term cognitive outcomes.
If I were to offer what all of this means to me as of October, 2023,
I am comfortable saying the following:
- Untreated hearing loss increases the risk of cognitive decline in many at-risk people.
- Professionally fit hearing aids often appear useful regarding altering the trajectory of cognitive decline in high risk, willing and able people.
- Just like in all other areas of medicine and healthcare, early detection and treatment is the most successful and most likely route to success.
Written By:
Douglas L. Beck, Au.D.
Doctor of Audiology
Excellence in Audiology Contributor
Fellow-Baby Boomer
