We’ve previously reported on research showing that hearing loss is a risk factor for cognitive decline and dementia. Now comes the strongest evidence yet that hearing loss is not only linked to cognitive decline and dementia, but that the use of hearing aids may help protect the brain from these conditions of advancing age.
Findings: Hearing aid use reduces brain function decline
Results from a recent study from the SENSE-Cog Project “found a reduction in the rate of cognitive decline following hearing aid use, suggesting that effective identification and treatment of age-related hearing impairment may have a significant impact on age-associated cognitive trajectories (Figure 1 below) and possibly reduce the incidence of dementia,” reports an article in the January 2019 edition of The Hearing Review.
Figure 1 Predicted values of episodic memory before and after beginning to use hearing aids (time centered at using hearing aids) *
How does hearing affect the brain in the first place?
First, we to understand how the brain processes sound in adults without hearing loss. Researchers have studied and continue to study how and where sounds are processed and perceived by the brain. They've found that there's a link between hearing and cognition-the brain's process of perceiving and understanding.
Thanks to magnetic imaging, scientists can watch the brain and see how it activates in response to certain sounds. They've discovered that we don't hear with just one part of our brain. The process of hearing also stimulates other brain areas. Scientists believe there's a dual-track association between hearing and cognition. Sound activates the auditory cortex; the cerebral cortex and cognitive processes influence how we hear.
What happens to the brain when hearing is impaired?
Because there is a decline in sound stimuli and sensory deprivation, hearing loss can lead to structural and functional changes in the brain. These structural and functional changes can affect the brain's capacity to process and perceive sounds and may contribute to cognitive decline.
The brain is forced to compensate for these losses by activating alternative circuits. It enlists accessory neuron networks and that means increased cognitive effort is needed to weed out irrelevant sounds, like background noise, and more concentration is needed for hearing.
A high cognitive effort reduces the amount of brain resources available to process everything else. There's less of a cognitive reserve to tap into. So, things like concentration, memory and planning capacity may be affected. It's easier to get distracted. And constantly decoding and processing sounds can take up a lot of mental resources which can be tiring, eventually leading to potential withdrawal from social interactions.
The significance of the hearing aid connection
The SENSE-Cog study stands out from previous research because it compares cognitive changes before and after hearing aid use in the same hearing-impaired individuals. (Older studies compared cognitive outcomes in hearing aid users and non-users.) Authors of The Hearing Review article “found compelling evidence to suggest a link between hearing aid use and slower cognitive decline.”
They also offer possible reasons for the connection between hearing aid use and reduced cognitive decline. According to one hypothesis, hearing aid use “may reduce depression, promote cognitively stimulating engagement (and) promote greater physical activity and/or self-efficacy, all of which protect cognitive function.” Another hypothesis is based on hearing aid use reducing the adverse impacts of sensory deprivation on brain function as mentioned above.
Good hearing health goes beyond the ears
The SENSE-Cox Project study “suggests that improving (the) prevention, identification and treatment of hearing impairment may help to delay the onset of cognitive impairment and reduce the impending dementia epidemic,” states The Hearing Review article, which concluded with: “Good hearing health may be critical for good cognitive health.”
The SENSE-Cox Project study underscores the importance of recognizing and treating a hearing impairment to protect your brain function. Adding hearing screenings to your preventive health routine can help you detect changes in your hearing allowing for prompt treatment to keep your hearing-brain function intact. Request an appointment with a provider near you today.
* Maharani A, Dawes P, Nazroo J, Tampubolon G, Pendleton N, on behalf of the SENSE-Cog WP1 group. Longitudinal relationships between hearing aid use and cognitive function in older Americans. J Am Geriatr Soc. 2018;66(6):1130-1136.