People who are hard of hearing spend more energy listening. That energy comes at the expense of other cognitive functions. Cognitive functions are the mental processes in the brain that enable us to think and solve problems, among other things.

In a new study featuring data from 573,088 people, researchers from the Department of Clinical Research at the University of Southern Denmark have found a link between hearing loss and the development of dementia. The study is the largest of its kind to date.

There is already an increase in the number of people with dementia. This is mainly due to the ageing of the population as a whole, but there are also other risk factors, such as lifestyle and hearing. 

- Previous studies have suggested that there could be a link between hearing loss and dementia. Our study is larger than the previous studies, and we have demonstrated a link between hearing loss and dementia, says Assistant Professor Manuella Lech Cantuaria from the Department of Clinical Research at the University of Southern Denmark.

Good news for hearing aid users

The results of the study show that people affected by hearing loss have up to a 13% higher risk of developing dementia compared to people with normal hearing. The high risk is especially seen in people with severe hearing loss.

The researchers also studied whether there was a difference in the risk depending on whether or not people wear hearing aids.

- We found that the risk of developing dementia was 20% higher for people who didn’t wear hearing aids compared to people with normal hearing. People who used hearing aids had a 6% increased risk of developing dementia. This suggests that wearing a hearing aid can prevent or delay the development of dementia, explains Manuella Lech Cantuaria.

About the study

The study is a so-called cohort study that follows a group of people with common characteristics over a longer period of time. In this study, all of the people were above 50 years of age and from the Region of Southern Denmark between 2003–2017. People diagnosed with dementia before the commencement of the study were excluded. The researchers compared data on people’s hearing with data on the development of dementia during the period. The researchers have found a significant – that is, clear – correlation between hearing loss and the development of dementia.

• The greatest risk of developing dementia was especially seen in people with severe hearing loss
• Hearing loss causes a 7% increased risk of developing dementia
• People with severe hearing loss have up to a 20% increased risk of developing dementia compared to people without hearing loss

Hearing loss and dementia

Hearing loss – a national scourge
Around 800,000 Danes suffer from hearing loss. And that number is only likely to get higher in the future because we are getting older in general, and we are exposed to more and more noise. Hearing loss is measured in decibels (dB). There are different degrees of hearing loss. For example, hearing loss above 60–70 dB means you can’t hear normal speech. Above 90–100 dB means you can’t hear shouting. 

Dementia
Dementia is a term used to describe the weakening of mental abilities due to illness in the brain. Dementia is characterised by an impairment of cognitive functions such as: Impaired memory and concentration, impaired orientation, language disorders, personality and behavioural changes. Alzheimer’s, for example, is a type of dementia.