New ‘brain hearing’ test could transform early dementia diagnosis, study shows 

How does the test work?

The nonverbal ‘brain hearing’ test asks people to identify one sound played into one ear while a different sound is played into the other. The task reveals how effectively the brain separates and interprets competing noises, such as when in a busy environment like a restaurant.  

The study was funded by Alzheimer’s Society and involved nearly 90 people, including those with Alzheimer’s disease, frontotemporal dementia and language-led dementia (primary progressive aphasia) as well as a group of healthy volunteers. It found patients with most forms of dementia performed worse using the nonverbal test.

Participants were played one sound (such as pouring liquid) to the left ear at the same time as a different sound (such as thunder) was played to the right. The brain had to separate these competing sounds and the person pointed to pictures matching the sounds. The test results across all participants aligned closely with people’s real life hearing experience and with the brain-related changes seen in their conditions in those with dementia.  

These results, published in Alzheimer's & Dementia: The Journal of the Alzheimer's Association, suggest that the nonverbal test could reliably distinguish those with dementia from those without and it was particularly accurate in identifying Alzheimer’s disease.  

Some of the data reported in the paper came from a National Institute for Health and Care Research (NIHR) funded study.

Hearing challenges can be even greater for people with dementia

Dr Chris Hardy, joint lead author of the study, said: 'We hear with our ears, but we also hear with our brains, and dementia can affect how the brain interprets sound, even when the ears themselves are working normally.

'When we’re in a busy environment, such as a pub or restaurant with lots of people talking, the brain must work hard to focus on a single voice. That’s an example of the type of ability we refer to as ‘brain hearing’. This is challenging for everybody, but this study shows that it’s even harder for people with a form of dementia, like Alzheimer’s disease.'

Improving diagnosis across communities

Standard dementia assessments are often over-reliant on words, which can be problematic, especially for diverse groups who may communicate in different languages. Because this new test avoids language altogether and uses images, it may help improve the dementia diagnosis experience and accuracy amongst culturally or linguistically diverse communities.  

Michelle Dyson CB, CEO at Alzheimer’s Society said: 

Now the first treatments that can slow Alzheimer’s disease are emerging, early and accurate diagnosis has never been more important.  

'With further research in larger, more diverse populations, a simple, accessible test like this could be used by clinicians in the future to support a diagnosis alongside other cognitive tests and clinical observations.  

'A clinical test like this could also help us interpret the results of other, laboratory-based tests for Alzheimer's disease.'

Hearing loss alone is not evidence of dementia

The researchers emphasised that hearing loss alone is not evidence of dementia. While hearing loss may be both a dementia risk factor and an early symptom in some people aged between 40 and 65, this study shows which brain mechanisms are affected, but not that general hearing loss is a warning sign of dementia.  

Dr Chris Hardy adds: 'Understanding whether hearing loss is associated with the ear or the brain is critically important; if you have brain hearing loss, but not peripheral hearing loss, then hearing aids are unlikely to help.'

While the results of this research offer hope for dementia diagnosis, they also underline the vulnerability of hearing for people with dementia.

Jason Warren, Professor of Neurology and Consultant at the UCL Queen Square Institute of Neurology and senior author of the paper, said:

Hearing, more than any other sense, connects us with other people.

'Hearing loss greatly impacts the wellbeing of people living with dementia. Many people with dementia find themselves sensitive to sound and begin avoiding noisy places, which can limit social activity. As this study highlights, we ought to explore how to make listening spaces and communication more accessible, so people don’t become isolated.'

Further studies will be required to assess the potential use of more sounds and sound combinations as part of this non-verbal hearing test, as well as the suitability of this new hearing test in a mix of people who communicate in many different languages.