Subtle hearing loss while young changes brain function, study finds

Jeff Baller, Au.D., CCC-A Hearing Health, Hearing Loss

Jeff Baller, Au.D., CCC-A

A recent study has shed light on the relationship between hearing loss and memory. We already know that the two conditions are related, but past research has been unable to determine if one condition is causing the other or if they simply tended to happen to the same people, particularly in older age. 

In general, those with mild hearing loss have double the likelihood of developing dementia, and those with moderate or more serious hearing loss have three to five times the risk of developing dementia. Although they are closely related, researchers wondered if hearing loss was actually causing dementia or if a third, unknown condition might be responsible. 

Recent research from Ohio State University is pointing the direction toward understanding the connection, but the study did not involve elderly subjects or people with dementia. Instead, they observed young people between the ages of 18 and 41. Let’s take a look at the study and look deeper into the possible connections they may be revealing. 

The Study

This recent study under the direction of Yune Lee, assistant professor of Speech and Hearing Science, did not set out to study hearing loss at all. Thirty-five subjects were recruited in order to observe what parts of their brain became active while processing information. 

The general plan for the study was to read sentences to the research subjects with varying complexity and to monitor how their brains responded. The researchers were curious what parts of the brain would become active when a very complex and difficult sentence was read as opposed to a simple and straightforward one. 

At the outset of the study, the team measured hearing ability to make sure that hearing loss was not getting in the way of the participants understanding the sentences, a basic control measure. However, once they had the hearing profiles of their research subjects, the researchers noticed a surprising pattern. 

When we are young, we tend to process language through the left hemisphere of the brain. As we get older, however, we tend to process language through other parts of the brain, including the right frontal cortex, and this shift tends to happen after the age of 50, on average. However, these researchers witnessed a striking pattern. 

Using fMRI technology to image the brain’s activity while listening to these various sentences, those who had mild hearing loss in this young age group were already beginning to use that other part of the brain: the right frontal cortex. Although they did not expect to witness this pattern, even participants with very subtle hearing loss had already begun to use more of their brain’s resources to process information. 

The Interpretation

With a limited sample size, researchers are not yet able to make decisive conclusions. However, these results are suggestive of the relationship we already know exists between hearing loss, memory, and even dementia. Lee is now wondering if hearing loss increases the cognitive load on the brain, demanding more resources to process information and to make meaningful units out of speech. 

When the brain is taxed in this way, it is possible that other functions, such as memory recall, might become more difficult. By witnessing the movement of brain activity to other areas, these researchers might have been witnessing a greater cognitive load taking place. If the brain were overloaded for too long, then cognitive decline including dementia might be more likely to occur. It is important to remember, as well, that these young research participants only had mild or subtle hearing loss. 

Young people like these are particularly at risk for hearing loss from loud “recreational” sounds. With the uptick in usage of headphones and earbuds in recent years, young people are exposed to louder sounds for longer duration than older generations experienced. With the possibility of hearing damage among an entire generation, it is more important than ever to take steps to protect one’s own hearing. 

Limiting the use of these recreational devices, as well as exposure to loud sound at concerts and sporting events, might even make it possible to prevent memory loss and conditions such as dementia and Alzheimer’s much later in life.  

If you are concerned about your hearing abilities, contact us today to learn more about our comprehensive hearing health services.