Lately there has been a lot of discussion surrounding hearing loss and cognitive decline. Many patients will arrive at their appointment for a routine hearing test, and this topic is already top of mind. Common questions include, “Does hearing loss cause dementia?” and “By treating my hearing loss can I prevent dementia later in life?” Truthfully, hearing loss on its own cannot tell us everything we need to know about your cognitive health, as there are many health and lifestyle factors that can play a role in this. However, hearing loss is known to be one of several risk factors for dementia. Thankfully there are some modifications that can be made in the mid-stages of life to potentially delay or prevent the onset of cognitive decline. Therefore, it is important to understand your hearing health and your options to treat hearing loss when looking at the big picture of your overall cognitive health.
How does dementia affect hearing?
When thinking about hearing loss and cognitive decline, it is helpful to think of your hearing as a two-step process. The first step is the physical detection of sound; this happens at the level of your ear. Once your ear detects a sound, it will transmit that information up your auditory nerve to your auditory cortex, which is the part of your brain you use to interpret sounds. The interpretation of the sounds you hear is the second step in the process. So, there is your physical ability to hear, and then there is your ability to understand what you hear. We detect sound with our ears, but we understand sound with our brains.
When there is an issue with the first step in the system, the hearing loss can usually be treated. Audiologists can detect gaps in the full range of sounds needed for conversation through testing and can typically treat the condition by using hearing aids that have been properly fitted.
However, when an individual is dealing with a cognitive impairment in addition to a hearing loss, it can create additional challenges. Because step two of the system – the processing of auditory information – is impaired also, it means that even with properly fitted hearing aids the brain may still not make all the right connections. The individual may be hearing the conversation at hand, but they may not be understanding all of it. In this case, implementing communication strategies (in addition to treating the hearing loss) can go a long way. These strategies include having conversation partners speak more slowly, clearly, and with good visual cues for the listener.
How hearing loss may change the brain
It has been determined that even a mild to moderate hearing loss can produce physical changes in the brain.
The first change observed is with the density of the gray matter (the material that makes up the outside of your brain, or cerebral cortex). The gray matter in the auditory cortex decreases in density when it is not getting appropriate stimulation. This is similar to when we need to wear a cast for a broken arm or leg. The cast helps to heal the bone, but the muscle inside may weaken over time because it has not had any stimulation. Our auditory cortex is like a muscle for our hearing that is not getting enough stimulation as a result of a hearing loss.
The second change observed in the brain is a relocation of cognitive resources. When our brain does not get enough information through hearing alone, it begins to reorganize itself to rely on other information. In the case of a hearing loss, the brain begins to reorganize some of its portions used for auditory processing to process visual information instead. The brain is trying to use visual information such as lip-reading cues and facial expressions to fill in the information it is not hearing. Considering this is not the original design of the system, your brain has to work harder to process this information.
What about tinnitus and Alzheimer’s?
While hearing loss is considered a risk factor for cognitive decline and dementia, there is another complication that hearing loss can often create. For many, a hearing loss – especially an untreated hearing loss – can mimic cognitive decline.
Imagine you are having a conversation with someone and as you chat you realize that some of their answers are not quite correct for the question you asked. Or perhaps they do not seem to be really following along with the conversation. It can sometimes be difficult to tell if the cause of the misunderstanding is due to impaired processing as a result of a cognitive decline, or if the person simply cannot hear you well. The observation of misunderstanding is the same, but there could be two very different causes.
Another way this can manifest is when a person with a hearing loss recalls information. Imagine you are out to dinner with friends or family, and you spend the evening swapping stories. Now imagine one of the members of that group was dealing with a hearing loss. If you were to get back together with that individual later and ask them to recall one of the stories discussed at that dinner, they may have difficulty doing so. However, in this case it is likely because they had trouble hearing the story in the first place so they could not properly store that information in their memory banks, which in turn makes it more difficult to recall. In this instance, the recall issue is due to a hearing loss, but if it was not known that a hearing loss is present it could certainly be mistaken for cognitive decline.
Often, when assessing for cognitive decline, a doctor will ask a patient to complete a series of screenings or tests. Consider that the person being assessed has a hearing loss, and the instructions for the test are given verbally. If the patient does poorly on the test, is it because they did not understand the instructions due to a cognitive impairment or because they could not hear the instructions well to begin with? What if the test itself is a series of verbally administered questions? One can quickly see how a hearing loss could impact those results in a way that does not truly reflect the individual’s cognitive abilities.
Do hearing aids reverse cognitive decline?
There is no guarantee that by using hearing aids cognitive decline can be reversed. However, it is known that hearing aids can have a positive impact on many elements that can factor into cognitive decline.
As previously mentioned, hearing aids help to ensure that the auditory cortex is receiving proper access to speech information. This allows for the best opportunity to process and understand speech. Think of your auditory cortex like a muscle – you need to continue to keep that muscle group active, or it will weaken over time. Using hearing aids is like exercise for the auditory cortex. It may potentially help to return strength to the system, but if there is already damage to the system there may be no way to return it to full strength. Then the focus turns to maintaining the current health of the system as long as possible, and potentially delaying future decline.
Additionally, hearing aids help to keep individuals engaged with their surroundings. Poor hearing can often lead people to gradually isolate themselves. It becomes more and more work to go out to social gatherings if hearing is a challenge, and not attending those events at all can become more and more appealing over time if the hearing loss is not addressed. This isolation can often trigger negative emotions such as depression. Negative emotional states, such as depression, have been linked to cognitive decline. By treating a hearing loss with hearing aids, individuals gain the confidence to resume attendance at social events, which can have a positive impact on their emotional well-being.
Hearing Aid Myths That Hold You Back
One of the biggest misconceptions about hearing loss and hearing aids is that hearing aids will not help until a hearing loss is very pronounced. Most people on average wait 5-7 years after noticing challenges with their hearing for their hearing loss to be “bad enough” to need hearing aids. Truthfully, the earlier you treat your hearing loss, the easier, and sometimes more beneficial the process is. By waiting to treat your hearing loss you are simply working your system much harder than necessary.
Another common misconception is for people to assume their hearing loss is normal for their age, and therefore there is no need to take further action. While it’s true that hearing loss is commonly seen in an aging population, hearing is either normal or abnormal. The hearing loss should still be addressed and treated, whether it occurs at birth or age 100.
A common misconception about hearing aids is the assumption that all hearing aids are the same. There are a wide variety of hearing aid technologies, and a person may be better suited for certain types of hearing aids depending on their hearing loss, their lifestyle, and their listening needs. There are many factors to consider when choosing the right hearing aid for you.
Similarly, the professional helping to select the hearing aids for you, and adjusting them for your particular hearing loss is an important piece of the puzzle. A hearing aid is a medical device, and therefore the best outcomes occur when it is fit by a professional who has training and expertise on the subject. Buying a hearing aid online or over the counter can leave a lot to be desired because there is no support to adjust the device to your specific circumstances. Listening needs change throughout your life. Depending on how your lifestyle evolves, it is important to have a care team involved to support you over the life of your hearing aids.
The Dangers of Untreated Hearing Loss
As we have highlighted already, hearing influences many aspects of your well-being. Leaving a hearing loss untreated can have larger implications than simply having to ask people to speak up or repeat themselves.
Untreated hearing loss can lead to social isolation and depression. It can cause communication barriers with loved ones, which can impair relationships over time. When it becomes more difficult to understand conversation, an individual needs to work harder to follow along. This additional effort can lead to exhaustion and fatigue. Untreated hearing loss can also cause safety concerns, as awareness and alertness may be reduced, and it may be more difficult to locate sound sources in your environment.
Hearing loss is beyond just a problem with the ears – it can lead to poor understanding and processing of auditory information. When left unresolved, a hearing loss can even lead to physical changes in the brain and a reorganizing of the auditory pathways. This means the brain needs to work harder to process auditory information. All these factors together can put an individual at a higher risk for cognitive decline.
It is important to get a baseline hearing test in middle age and continue to pursue routine hearing tests after that to detect a hearing loss as it emerges. Early implementation of treatment with a trained professional is an important step in managing a hearing loss for the best outcomes.