The study took place in the region of Southern Denmark from 2003 to 2017 where researchers focused on the link between hearing loss and developing dementia. Information on participant hearing was collected from hearing clinics and combined with dementia data. The median follow-up time of the participants was 10 years (range, 0.25 to 15.0 years)², which is considerably higher than the norm.

A spotlight on hearing intervention

The findings of the SDU study build upon, and strengthen, those of its predecessors: that hearing loss is associated with cognitive decline, specifically the development of dementia.

The study's researchers found hearing loss was associated with a 7% higher risk of dementia, which increases to 20% when left untreated. These findings further support the theory that hearing loss may increase the risk of developing dementia, especially when hearing aids aren't used – study authors suggest that treating hearing loss with hearing aids may reduce this risk3.

"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. This suggests that wearing a hearing aid can prevent or delay the development of dementia."

Manuella Lech Cantuaria
Assistant Professor, Department of Clinical Research
University of Southern Denmark

Not only does this insight add to existing evidence, but it can also be leveraged in the growing case for better dementia prevention strategies that require a deeper understanding of the link between hearing loss and dementia.

Another insight to be gleaned from this study lies in the way it was set up. Following more than half a million people during a total of 14 years is unprecedented in studies of hearing health and dementia risk. As the authors state, this choice of study design allowed for a more representative study population than many studies that came before it.

As a result, the SDU study can be seen as an important contribution to the body of evidence thanks to its size, follow-up period and representative sample. Studies of this kind work towards ensuring everyone in the field is working from the best possible vantage point.

Inclusion / exclusion criteria

• Included all residents of Southern Denmark 50+ years old

• Excluded individuals who:

• had dementia before baseline

• did not leave in the region five years before baseline

• had an incomplete address history

had missing covariate information

Data collection method

• Compared data from public hearing rehabilitation clinics on people's hearing with register-based data on the development of dementia during the study period

• Collected individual-level data of covariates (country of origin, cohabitation, education, income, occupational status) in collaboration with Statistics Denmark

Further study results

• Individuals with hearing loss had up to a 13% higher risk of developing dementia compared to people with normal hearing

• Individuals who used hearing aids had a 6% increased risk of developing dementia, which is down from the 20% high risk for people who had hearing loss but didn't wear hearing aids

Next steps in brain health research

So where does this new research leave us? Well, the question now perhaps is no longerwhetherthere's a relationship between hearing health and brain health. But rather,howdoes hearing loss affect the brain? And, perhaps even more pressingly – how can the cognitive risks associated with hearing loss be reduced?

With these questions in mind, we can expect to see more and more high-quality studies examining the specific effects of hearing loss on the brain. As well as the influence that wearing hearing aids may have on this.

The authors of the SDU article themselves state the importance of more research around the connection between dementia and hearing loss. And part of the LISTEN TO THIS mission is to monitor the field as it develops and highlight the essential updates as and when they happen.

Ultimately, we may well reach a point out in the future where it can be confidently claimed that using hearing aids will reduce the risk of developing dementia for people with hearing loss.

Looking to the future

Keep an eye out for the next edition of this BEYOND THE DATA series for a new research digest in the escalating hearing and brain health story. Read more insights on hearing and brain health.

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