Enhancing Cognitive Health with Hearing Optimization

Shally Yuan, Audiologist at Phonak Canada, transcripts from our 14th Annual Healthy Hearing Expo. Transcripts have been edited for clarity. 

Audiologist Shally Yuan from Phonak Canada, speaking about hearing and cognition.

Your Hearing and Cognition

One of the things I want to talk about is cognition and the term dementia. We’ll delve into the details about cognition and defining those terms. Dementia – what does that mean? We’ll tie it into a relationship with hearing and go into the latest studies and research linking the topics.
Now I want to start with a little thought experiment. What is important for your health? We have these things that Google, your doctor and media tell you is good for your health.

Not smoking, no alcohol, vaccination, social support, exercise, physical activity, healthy weight, medication and less air pollution.

It turns out what is most important might surprise you. It is social support, and social integration.

What is social integration?

Social integration is feeling part of a group. Maybe a book club or your church. It’s a bit different than just socializing. The sense of belonging. So, the top two are social support and social integration which could be very surprising. You are probably thinking this is a talk about cognition and hearing. What does being social have to do with it?

Think about how much socializing requires being able to hear. Hearing aids enable social connections. You will see later what an important role being social has for healthy aging and cognitive health. I’ll define the relationship between hearing loss and cognition.

What do we mean when we say cognition? It refers to the mental action of acquiring knowledge and understanding through thought, experience and senses. It’s a wordy definition but I think of it as using your brain, experiencing, thinking, feeling. Everything to do with processing the world around you. That’s cognition.
We know cognition changes with aging. The brain changes as we age. Cognitive change is normal. Not everyone experiences the same degree of cognitive change. But our brains do change and some of the effects include a slowing of the information processing speed and reduced capacity of working memory. We also have greater effort required and difficulty dividing or switching attention.

You have probably experienced this change in some way. It’s not as easy to think and keep up as it used to be. Remember what I said earlier about this rate of change – it doesn’t happen the same way or at the same rate for everyone.

Mild cognitive impairment is what some people experience where their cognitive function goes down faster than what we’d expect with normal aging, but not as severe as dementia.
What is dementia? Dementia is a rapid drop-off of cognitive function compared to normal aging. The world is thrown around a lot in the media. It’s an umbrella term for a spectrum of brain disorders.
Everyone is probably familiar with Alzheimer’s which is just one type of dementia. Maybe you’ll have seen Bruce Willis and Wendy Williams who were diagnosed with fronto-temporal dementia. When Robin Williams passed away, they found he was in the stage of Lewy Body Disease, another form of dementia. Alzheimer’s is the most common form.

Some people think it’s a memory disorder. That’s not the only thing that it effects. Dementia can affect all parts of your life including language abilities. People with dementia find it hard to communicate because it affects their language. It can also affect motor skills, executive function skills, things like looking at a pot and knowing it’s for cooking and not putting over your head. Those are ingrained in your cognition.

So dementia is gradual deficits in the ability to perform everyday tasks. It affects more than just your memory. Lastly, it’s relatively permanent and irreversible.

So, what are the warning signs of dementia? Let’s start with what is normal aging – cognitive changes related to aging. It’s normal to forget the names of people you rarely see. Briefly forgetting part of an experience or not putting things away properly. Mood changes, or changes in interest. These are normal changes in cognition.

For dementia, be on the lookout for forgetting the names of people close to you, like your kids, grandkids or spouse. Forgetting things more frequently. Repeating phrases or stories in the same conversation. Unpredictable mood changes. Maybe someone used to be very gentle and now gets upset over things they would not normally be upsetting. A decreased interest in activities and difficulty making changes or multitasking. Before they used to do that easily. Now why is dementia such a relevant topic? It’s because there’s a huge cost to society.

There are currently 55 million people living with dementia. That’s expected to go drastically up by 2050. The cost to society is over $1.3 trillion dollars including costs of caregiving, medication, caregivers taking time off work. Over 60% of all dementia cases are Alzheimer’s.

Because of this huge cost to society, it has gotten the attention of governments around the world who are looking into ways of reducing or delaying the onset of dementia.

This is where we tie in hearing. We know the ears (hearing) and brain (cognition) are equal partners. The ears pick up the auditory signals but it’s the brain that gives meaning to the sound. If you think about it in terms of vision – you can see everything. But the way you know what something means is putting meaning to something you see. It’s the same way with hearing – your brain gives meaning to all these signals being picked up. We know the better quality of an incoming signal, the better chance you have to make sense of it and be able to comprehend it.

We need to give the brain as clear a sense as possible. We also know hearing loss impacts wellbeing. Hearing loss reduces audibility. This reduces environmental awareness and increases fatigue and anxiety. People say “I’m getting by OK” but research says that hearing loss does increase listening effort, fatigue and anxiety. So, what that can lead to is challenges in maintaining attention because your brain has to spend more resources on listening.

So, in some extreme cases – you don’t want to socialize. I have heard people say, “I don’t want to bother going to the restaurant because I can’t hear – what’s the point?” That can stem from an untreated hearing loss.

I want to take a moment to recognize hearing is not the only factor that goes into cognition. There are other factors as well – pain, stress, etc. The talk we are focusing on today is hearing and how that can play a role.


To summarize – the ears and brain are equal partners. The greater the hearing loss the harder it is for the brain to put the overall picture together.

We know cognitive changes are normal with the aging process and hearing loss does have an influence on cognitive performance.

Now we’ll go into why treating hearing loss is so important for your cognitive health. In this section I will present some of the research that is out there. Before we go into the evidence, when you google Hearing or Dementia, because it’s the internet – they like to put a bit of fear in you. They sometimes make things sound worse than they are. This is what I hope this talk will get across to you today; there is a link, but don’t be afraid. There are things you can do. I want you to not fall down the rabbit hole of googling. Sometimes I type, “I have a headache” and it tells me I have two days to live. Don’t go down that path. We’re going to be evidence based here.

Before I go into the evidence, I want to tell you and differentiate between the terms risk and association. This is in a lot of health research studies. They love “risk” and “association.”

Risk doesn’t mean it causes something. Risk just means it increases the chance or probably of something happening. Having untreated hearing loss increases the risk of developing dementia, but it does not mean having untreated hearing loss will cause dementia. Same with association, it means that in the studies, they see people with untreated hearing loss are more likely to have dementia, but they have not proven that untreated hearing loss is causing dementia.

Causation is what we’re after. What we can say, in the hearing world, is that too much noise exposure causes hearing loss. We know that definitively. We have seen loud noise damages the cells in the ears and causes hearing loss. So, we are able to use causation here. Noise exposure causes hearing loss. For the other two, it is just risk and association.

To illustrate risk and association, I want to tell you a fact. In the Middle Ages, did you know they thought having lice was an indicator of good health, because they never found lice on sick people? What was the case was that lice are sensitive to changes in temperature. Everyone who had a fever didn’t have lice because the lice jumped to healthy people.

If you took that example, you would think, let’s put lice on everybody. I want to emphasize the dangerous of putting too much weight on the terms ‘risk’ and ‘association’. I don’t want you to think oh, I don’t have to worry about it, because things like smoking and lung cancer were a risk until they found it was causation. It’s something to be aware of but not panicked of because it has not been shown to have a causal relationship.

There is an association between those who are low socioeconomic status and have lung cancer. It’s more likely that people have socioeconomic status were more likely to smoke and have higher exposure to air pollution. That contributed to the lung cancer, not the socioeconomic status.

I spent a lot of time on that because it will become important as we go into the evidence later. Now, I want to talk about the potential pathways – and I say potential because these are just theories. These are what researchers are thinking could cause the relationship between hearing loss and dementia.

The first is cognitive load. If you have hearing loss and you’re not getting a clear signal to the brain, the brain must divert the resources for listening away and into the hearing. From that, the cognitive load theory is how hearing loss and cognitive impairment are related.

The second theory is sensory deprivation. When you have hearing loss, the theory is that it might change the way your brain behaves. There have been studies where they found that people who have hearing loss, the structure of their brain changes. They’ve done scans of people with normal hearing vs hearing loss, and they found changes in the structure of the brain for people with hearing loss. Sensory deprivation can change the way your brain functions and that could impact your cognitive function.

The third is social isolation. Having hearing loss impacts your ability to be social. You’re not getting as much input and stimulation if you don’t socialize with people. Humans are social creatures. We need that social time. Hearing loss impacts your ability to be social, which can impact cognitive function.

The fourth theory are common pathological processes. There could be another thing we haven’t discovered that could affect hearing loss and dementia at the same time. We haven’t found a causal relationship. We have some theories about how they’re related, but there could be another thing that’s unknown that is impacting both hearing loss and cognition.

This is a study in The Lancet. They investigated factors that could affect dementia because dementia is a big cost to society, and governments would like to keep the costs down. They were looking at different factors that could contribute to dementia. They found twelve factors that accounted for 40% of dementia cases.

This means that 60% of dementia cases were inevitable. There was nothing that could prevent those 60% of cases. The 40% they found, there were twelve factors they found contributed to those cases. They were risk factors; hearing loss, less education, smoking, depression, social isolation, air pollution, physical inactivity, heavy alcohol use.

You will notice that hearing loss is the topmost modifiable risk factor. When I say modifiable risk factor, it means potentially we have the power to do something about it. The theories I talked about kind of make sense about why doing something about your hearing may help. If you have well-fitted hearing aids, that is going to free up your cognitive load, so now you don’t have to spend as much time on hearing and your brain has more cognitive resources. Also, you’re getting that sensory input as well with fitted hearing aids and that can be a modifiable risk factor.

It’s important to know, this is an observational study. They said this is what we notice in people with dementia. They have hearing loss, perhaps doing something will help. This was not an actual scientific experiment. We haven’t had any evidence like that until last year.

Last summer, there was a research study being done that presented very interesting results. It was a type of study that hadn’t been done before. All these things I just said – risk, associations – we haven’t had any type of experiment to prove causation. To prove causation, you need a type of experiment called a randomized control trial. That’s the best evidence. We haven’t had that until now.

I have to say, one experiment is not going to make the issue, but it’s exciting that we’re finally seeing this type of study. A randomized control trial means they take a group of people and randomly assign you to a condition or no condition. In this study, they took about 1,000 people and randomly assigned half to have hearing intervention, like hearing aids, and randomly assigned the other half to health education, like healthy eating classes and exercise. They didn’t get hearing aids, just healthy eating and exercise.

The randomly assigned part is important. If you take a group of people and randomly put them in groups, you can really tell if the intervention is having an effect. If everything else is the same and one group shows improvements, we know it’s because they received hearing aids in this case. 1,000 people, half got hearing aids, half got health classes.

This experiment ran on for three years. They did cognitive assessments before they started and every six months during the experiment. They tested them again at the three-year mark. Did hearing aids help stave off cognitive decline?

Last year they published some results. It’s an ongoing study. First, they said no noticeable differences. If you got hearing aids or health education classes, it didn’t seem to affect cognition. They spent three years and didn’t find anything, but they had to do more analysis.

They had taken a special group to begin with. 75% of them they collected from the community. They were healthy volunteers, didn’t have preexisting conditions, their cognition was higher to begin with. The other 25% was from a heart health study. Those people were usually older, already had other preexisting conditions, their health wasn’t as good. When they analyzed the difference between those two groups, the heart health study participants vs those with healthy education, they found a 48% decrease in the cognition slow down if you received hearing intervention.

No significant difference for the volunteers. So, if you were at an increased risk for cognitive decline, hearing intervention slowed down the loss of abilities by 48% over three years. So, in that study, the heart health study participants – if they received hearing aids they did much better on those cognitive tests than their peers who only got the education piece. They were already at a higher risk of cognitive decline due to their age and health issues.

That’s very promising. We have had any studies showing this before. One study is not enough to prove a causal relationship, but I wanted to show you the evidence that is out there. They will need more studies to back this up. Even the volunteers who were healthy didn’t have their cognition affected – it could just take longer to show up.

So, they are going to run the study for longer to see if after more years there will be a difference for the healthy volunteers.

One randomized control trial, it’s a very good source of evidence but not enough to change our stance. But it’s very promising to see studies like that. This is another study that came from a different group. It’s an ongoing study. This is not a randomized control trial. There needs to be different types of studies to support the conclusion.

It is still very promising because it supports what the other study found. There was about 160 people. They gave half of them hearing aids and half they didn’t. They wanted to see what happened three years down the line. Cognitive tests were given before and after the experiment. They all had untreated hearing loss. Similarly, the cognition tests at the three year follow up was stable for the hearing aid users. For the other group the cognition declined. This study suggests that treating hearing loss with hearing aids may delay cognitive decline.

We can’t say it for sure, but we are starting to put the pieces together. Stay tuned as these studies go on and come out with new updated results. What does this research mean? Evidence is promising. Hearing aid use supports cognitive health, but we can’t yet talk about causality.

I want to end off on this note. If you don’t believe in the power of socializing for healthy aging – how many of you saw this documentary on Netflix? It’s called The Blue Zone. For those who don’t know a blue zone is these regions where there are a lot of people living to very elderly age – and not just living but thriving. They are involved in the community, aging healthily.

He goes to each region and interviews them. It’s not research but a good story. He talked to them all and asked, “what’s your secret?” He found there were four areas. They got a lot of exercise and moved – gardening, walking etc. They all had a positive outlook about life. It wasn’t like “ugh, I’m still here.” It was like “I am here and have a purpose!” They all ate very well. And lastly the connection part. They all had a huge community and were excited to be a part of it.

They were socially integrated with book clubs, church groups, arts and crafts clubs. That connection is an important piece as we age and how we can age in a healthy way.

I’ll summarize and end with a few things. There’s no causal relationship between hearing loss and dementia we can say yet. Hearing better can help you think better. It’s a big part of your overall health. Hearing tends to be overlooked. People don’t realize how much you are missing out on when you can’t hear well. So, hearing better can maintain social connections.

That part is important for healthy aging. I hope today you were able to see some of the research and really learn about it. If you had fears, I hope it gave some reassurance. I hope this was useful information and thank you for coming and for your time.

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