Home Swim wears Why hearing loss can cause dementia and how to prevent it, Lifestyle News

Why hearing loss can cause dementia and how to prevent it, Lifestyle News


Calvin Zhang’s inspiration for Incus, his hearing aid company, was drawn from his relationship with his grandfather, with whom he was very close.

“He taught me to play chess, to swim, to hunt, to plant watermelons.”

He noticed when his grandfather’s hearing loss got worse. He turned up the television volume louder and louder – but refused to wear his hearing aids.

Zhang would learn that his grandfather’s behavior was not unusual: In Hong Kong, only 5% of hearing-impaired people wear hearing aids because traditional devices are uncomfortable, noisy or inaccessible, he says.

With an interest in audio developed by his penchant for music, Zhang pursued a degree in signal processing so he could understand sound at a fundamental level.

He teamed up with Professor Richard So Hau-yue of the Hong Kong University of Science and Technology, who has devoted nearly 20 years to hearing aid technology.

They collaborated to find a way to effectively manage noise reduction in hearing aids so that wearers would be spared the buzz and fizz of older models.

They invented a device that mimics the human brain’s natural ability to drown out background noise and accentuate target sounds, such as speech or television sound.

And Incus was born – named after the small bone in the middle ear, sometimes called the anvil for its shape, which receives vibrations to be translated into sound.

Losing your hearing can be extremely isolating, says Zhang.

He considers it the second most important of the five human senses after vision.

Basic hearing loss reduces our ability to engage and communicate, and being hard of hearing leads to social isolation and loss of contact with loved ones, he adds.

Studies have found a link between hearing loss and depression, and a 2020 report in The Lancet journal that identified a dozen modifiable risk factors for dementia lists hard of hearing as an independent and significant factor.

According to this report, hearing loss accounts for up to 8% of dementia cases.

It’s not just the isolation that accompanies hearing loss that’s problematic, it’s also the added cognitive burden it brings.

If you have to really focus on your hearing, other cognitive systems, like your memory, will suffer.


Some research suggests that hearing loss can even lead to brain shrinkage.

According to the World Health Organization, more than 1.5 billion people worldwide live with hearing loss, a number that could reach 2.5 billion by 2030.

A 2019 study posits that hearing loss is a bigger risk factor for dementia than depression, social exclusion, diabetes or smoking.

Another study – conducted by doctors at Johns Hopkins University in Maryland, US – found that mild hearing loss doubled the risk of dementia.

Moderate hearing loss tripled it, and people with severe hearing loss were five times more likely to develop dementia.

This is tragic considering that hearing loss is often easily diagnosed and alleviated with hearing aids. When hearing deficits are treated with hearing aids, cognitive function can be boosted by up to 50% in just one year.

The latest figures available for Hong Kong suggest that around 155,200 people (around 2% of the population) had hearing difficulties in 2013.

Sometimes it takes a family member to gently encourage an older person to take a hearing test.

Chan Leung, 80, is a good example. His family encouraged him to take a hearing test when they noticed he was having trouble hearing and communicating.

A test established hearing loss and he was fitted with traditional hearing aids, which helped. But he didn’t like using them in busy environments because he didn’t like the background noise.

He now uses a pair of Incus Kite 2 aids with their special noise reduction technology.


Eed Shen, an audiologist at the ENT Laser Hearing & Speech Center in Hong Kong, says all children born in Hong Kong should be tested at birth “so that, if present, hearing problems can be detected early for prevent problems with speech and language development”.

She adds that it is recommended that most people have hearing tests carried out by their GP, pediatrician or ENT (ear, nose and throat) specialist if or when they experience symptoms such as ear discomfort, tinnitus, dizziness or lightheadedness, ear blockage or sudden ear or progressive hearing loss.

Although Shen sees some patients who want to have their hearing checked independently without a doctor’s referral, she says many seniors think hearing loss is normal in old age and don’t actively seek help or are not systematically tested.

They just live with it, not realizing how detrimental it could be.


According to Zhang, older people should start annual hearing tests from around age 60.

Statistics show that over the age of 30, a third of people already suffer from some form of hearing loss, he says.

A hearing test is easy and not uncomfortable, Shen says.

A standard hearing test, called pure tone audiometry, can indicate the degree of hearing loss as well as the type of hearing loss, whether it is mainly in the middle or inner ear, or mixed.

Audiologists are able to advise their patients on what they can hear and what they cannot hear, such as speech or environmental sounds, based on the results.

Hearing loss is described in decibels.


“People with normal, healthy hearing can hear lower decibels,” says Zhang, “but if you can only hear 40 decibels, there may be hearing loss. Sixty is more serious.”

Each ear is measured independently as hearing in each may be different.

Sometimes hearing loss can be the result of something simple, like earwax or an infection, and can be easily treated.

But any hearing loss requires an investigation by a professional for a complete diagnosis, to identify the situation and try to find its cause and extent.

Sometimes the hearing loss is permanent. Permanent hearing loss can be caused by prolonged exposure to noise levels above 85 decibels, such as a noisy work environment or listening to music at high volume.

Often this can simply be caused by advanced age.

We can’t do anything to age, but we can do something about hearing loss and thereby minimize our risk of dementia.

The solutions are becoming more and more comfortable and sophisticated.

What about Zhang’s grandfather today? He is 81 years old and is delighted with his Incus hearing aids, which he happily wears.

This article was first published in the South China Morning Post.