New evidence hearing and smell loss linked to dementia

There’s some new research connecting hearing loss and what might raise the risk of dementia later in life.

Physicist Joseph Ulmer, curriculum and program developer with Indus Space Inc., spoke to Tamara Cherry on The Evan Bray Show this week about a potential link between hearing loss and dementia. He pointed to a recent 2020 report from the Lancet Commission.

“People who suffered from hearing loss had a greater risk of developing dementia later on than other factors that are commonly associated with dementia like lack of education, smoking, traumatic brain injury, depression and social isolation,” said Ulmer.

Ulmer said the report goes so far as to say if hearing loss is completely eradicated from the world there would be “eight per cent less cases of dementia worldwide.”

“The fact is the more aggressive the hearing loss becomes, the more likely the cases of dementia, at least according to the Alzheimer’s Society of the UK, which says that like nearly double the amount of people with mild hearing loss will develop dementia compared to those with normal hearing,” said Ulmer. “Then more moderate is like three times the risk, and then severe hearing loss you have five times the chance of some sort of cognitive decline later on.”

However, researchers are not quite sure why this link exists.

Ulmer spoke of a few theories out there. One is the loss of hearing might cause the brain to redirect the synapses it uses for hearing and “rewire” the brain to run less efficiently. There’s also the idea hearing loss forces the brain to “redirect” more of its power to interpret information it is receiving.

Another possibility is the same neurological issues going on in the brain that cause dementia might also be causing hearing loss. So the hearing loss might be more of a symptom.

A final possibility, and one which Ulmer says is gaining more traction, is that people with hearing problems might “be more likely to pull back from social situations and become more isolated over time.”

Ulmer said having interactions with others and having regular conversations “stimulates important parts of our brain.”

“There’s a growing thought that perhaps that isolation and not using those parts of the brain regularly for social conversation accelerates the degrading of those key parts of the brain and could be a contributing factor to things like dementia.”

Those involved in addressing dementia say up to 40 per cent of the cases are preventable, and a healthy lifestyle is important. This includes managing such things as hearing loss.

Ulmer said Lancet is pointing to early intervention in hearing loss as being key to reducing the risk later on. That could include the use of hearing aids or cochlear implants which could slow down the loss of thinking and memory abilities.

“The trick though is that this needs to be done kind of early into the stages of hearing loss,” said Ulmer. He said people do tend to seek medical help for hearing loss, but “they tend to wait to go and see a doctor about it after they’ve gotten to a certain point where it’s really, really rough for them.”

At that point, having a hearing aid can stop things from getting worse, but “it’s probably already had an effect on their brain at that point,” said Ulmer.

Loss of smell

It is not only hearing that has a connection to dementia. Ulmer also points to a study that suggests the loss of your sense of smell is another factor.

“Much like vision and hearing — your sense of smell does also start to degrade with age,” said Ulmer. That is due, he said, to factors like pollution or smoking, but also viral infections.

“COVID(-19) has had a noticeable effect on people’s long-term ability to smell and taste things,” said Ulmer.

A loss of smell could impact the brain as well. Ulmer said loss of smell can lead to an increased risk of depression and “can be an early symptom of dementia or Parkinson’s disease.”

“Smells are really great to stimulate brain functions,” said Ulmer. “We can all relate to that feeling where you’re just randomly walking a certain day and then you smell a certain scent you haven’t smelled in a while and it instantly gets flashbacks to childhood whether it is a meal your mom would cook or just the ways books in your school would smell.”

Again, interventions are key. Ulmer said there are “nose-training” exercises to keep your sense of smell sharp. One way is to, a couple of times a day, seek out household items that could be in the vicinity “and spend 30 seconds just smelling it.”

By “household items” he is referring to items on your spice rank, or items like soap, toothpaste, honey, coffee, or even a glass of wine. By doing this regularly, it would help get your “nose memory” trained said Ulmer.

“Even if the results aren’t promising at first like you’re not noticing a lot when you first go at it, there is more evidence that doing this thing on the regular, like twice a day, will gradually improve your sense of smell over the course of many weeks and you’ll see a noticeable improvement in your ability to detect these things over time,” said Ulmer.