When we talk about hearing, we usually talk about our ears. But did you know that hearing actually happens in the brain?
Here’s a quick primer on how our hearing works: sound waves enter your outer ear and travel through your ear canal, where they are amplified in the middle ear and turned into vibrations. These vibrations make their way to the inner ear, where they are translated by inner ear hair cells into signals that are sent to the brain to be processed.
So, when a person experiences hearing loss, one or more steps in this process malfunctions, which interferes with the brain’s ability to register and recognize sounds. In recent years, a number of studies have linked untreated hearing loss with dementia, due to the cognitive load placed on the brain when it struggles to make sense of sounds.
According to Frank Lin, an otologist and epidemiologist at Johns Hopkins University in Baltimore, “The general perception is that hearing loss is a relatively inconsequential part of aging.” However, studies conducted by Lin and his team at Johns Hopkins have revealed far-reaching consequences of untreated hearing loss, including potential links between untreated hearing loss and dementia.
As we age, our brain tissue mass naturally decreases, but with untreated hearing loss, there is added strain to our brains in the form of a heavier cognitive load. In one study, Lin and his fellow researchers tracked the cognitive abilities for 2,000 older adults (with the average age of 77) over six years. Results show that 24% of test subjects were more likely to have diminished cognitive decline, compared to subjects with normal hearing.
In a separate study, Lin and his team followed 639 test subjects with normal, healthy cognitive ability at the beginning of the study, for 12 to 18 years. These subjects took regular hearing tests through the course of the study. It was found that the worse the subject’s initial hearing was, the worse their cognitive abilities were in the course of the study. This cognitive load placed on the brain increased the potential risk for dementia, according to researchers.
These studies found that untreated hearing loss creates a heavier cognitive load for the brain, which overcompensates as it attempts to keep up with muffled signals received. Over time, this “burden” on the brain, so to speaks, tires out the brain and its functions. At the same time, the disuse of certain neural pathways in the audiological process may affect brain function – often times in ways we are not completely clear about, such as memory and emotion.
The interconnected consequences of untreated hearing loss – heightened stress, anxiety, depression, and social isolation – are also considered triggers for dementia. At the same time, Dr. Lin clarifies, “I have a 92-year-old grandmother who’s had a moderately severe hearing loss for many years now. She’s sharp as a tack. I was talking to her about my research and she looks at me and says, ‘Are you telling me I’m definitely going to get dementia?’ I said, ‘Not by any means.’” Lin points out that “simply being at increased risk does not mean a person is certain to develop dementia.”
It is important, however, to do what we can to mitigate this risk, especially given the high rate of older Americans developing hearing loss. Currently, one-third of Americans age 65 or older experience some degree of hearing loss; 50% of people over the age of 75 experience hearing loss. With this in mind, hearing specialists recommend that people being annual hearing tests at the age of 50.
When we recognize someone’s voice or a few bars of music, this is due to the intricate auditory processing that happens in our brains. This processing also sets forth the next series of actions; for example, an ambulance siren tells us to pull over to the side of the road and a fire alarm notifies us of danger. When hearing loss goes untreated, the brain struggles to make sense of the sounds being transmitted, and often overcompensates.
If you’ve noticed changes in your hearing, take the first step toward improving your cognitive health. Schedule a comprehensive hearing test
at one of our Puget Sound Hearing Aids and Audiology. If a hearing loss is identified, we will work with you to find solutions to both support your hearing – and your brain.