Hearing Loss and Dementia
When we think about hearing loss, we often think about our ears. “My ears aren’t good as they used to be,” some may say. But, did you know that hearing loss actually happens in the brain?
As with all of our five senses, hearing is processed through tried-and-true neural pathways that process information from our external world and delivered to our brains, where we recognize familiar experiences – scents, tastes, and of course, sound. When sound waves enter our ears, it travels through the middle and inner ear and is transformed into an electric “signal” that is processed and catalogued in our brains.
With this understanding, it is important to note that untreated hearing loss does affect the way our brains function. Recent studies have pointed to a link between untreated hearing loss and an increased risk for dementia.
How Does Hearing Work?
Sound waves are picked up from the outer ear and travel through the ear canal. Then, sounds are amplified in the middle ear and sent on to the inner ear. Here, sound waves are translated by inner ear hair cells into signals that are sent to the brain to be processed.
The brain’s ability to process and recognize sound is what keeps us in touch with the world around us. Familiar sounds register in our brains through this process. This is how we recognize a favorite song, a loved one’s voice, a dog’s bark, or a fire alarm. In every part of our lives, our sense of hearing provides us with information about the world around us. With untreated hearing loss, the brain must work harder to make sense of this audio information.
Studies from Johns Hopkins Point to a Link between Untreated Hearing Loss & Dementia
In recent years, a number of studies from Johns Hopkins University indicate that there may be potential links between untreated hearing loss and dementia. The heavier work load for the brain, so to speak, is at the root of the issue in terms of hearing loss and dementia.
In one study, researchers tracked 639 test subjects over the course of 12 to 18 years. They found that subjects with untreated hearing loss were more likely to develop dementia over the course the study. Furthermore, they found that that people with moderate hearing loss had three times the risk of dementia than people with normal hearing. The team of researchers, headed by Dr. Frank Lin, posited that hearing loss creates a heavier cognitive load for the brain, which overcompensates as it attempts to keep up with muffled signals received, and therefore tires out the brain.
In another study, Dr. Lin and his team tracked the cognitive abilities of 2,000 older adults (average age 77) over a span of six years. In test subjects whose hearing loss interfered with conversation, researchers found that 24% of test subjects were more likely to have diminished cognitive decline, compared to subjects with normal hearing. In part, this may be due to the fact that when certain neural pathways are no longer in use, due to hearing loss, different areas of the brain may be affected. Overall, they found that untreated hearing loss accelerated cognitive decline.
In addition to the effects on the brain and cognitive abilities, hearing loss leads to social isolation. With untreated hearing loss, people struggle with verbal communication. Over time, difficulties with speech recognition may lead to the avoidance of social situations. Breakdowns in interpersonal relationships, due to miscommunications, could also lead to withdrawal from our most important relationships. Research on dementia and Alzheimer’s disease reveals that if we remain more socially engaged, we are less likely to develop dementia. Engagement with our friends and loved ones keep us active – and also our brains!