Tackling Hearing Loss as a Risk Factor for Dementia

According to a 2020 Lancet Commission Report, if you have hearing loss, you have a greater chance of developing dementia. There are different theories for why this is the case. Experiencing hearing loss can make the brain work harder in compensation, which can put a strain on other brain functions. Hearing loss is also known to lead to brain shrinkage as we age. This shrinkage may directly lead to cognitive impairment and dementia. Finally, hearing loss often leads to a lower level of social engagement, which can cause the brain to be less stimulated and active.

Dr. Björn Herrmann is a cognitive neuroscientist who leads the Auditory Aging Lab at Rotman Research Institute at Baycrest. He is also an Assistant Professor in the Psychology Department at the University of Toronto, and the Tier II Canada Research Chair in Auditory Aging. Dr. Herrmann’s research focuses on how we, as humans, engage in listening and communication as we age, what makes some people unable to engage, and what we can do to help people who develop aging-related hearing disorders.

Dr. Herrmann’s lab concentrates on two key aspects of hearing:

Auditory foundation, aiming to determine:

• how sounds are converted into meaningful signals that our bodies can react to
• how various processes in the brain support listening when encountering challenges
• how sensation and cognition interact to shape listening experiences

2. Auditory vulnerability, aiming to clarify:

• what happens in the brain when individuals develop hearing loss
• how can we reduce the cognitive impact of hearing loss
• how difficulties in understanding speech affect individuals’ social experiences, behaviours, and relationships

Standard hearing tests, that have been in use over the years, typically diagnose hearing loss decades after first struggles with speech comprehension in noise start. A deep dive - into both the physiological foundations and the psychosocial aspects of hearing loss - has helped inform the Auditory Aging Lab’s development of new approaches to detect and treat hearing loss earlier.

The lab’s complex, multi-faceted focus demands a myriad of research methods. These include, but are not limited to: brain activity recording devices, neuroimaging technologies, eye-tracking devices, computational modeling, and qualitative interviews.

It is said that our eyes are the window to the soul; more accurately, they are the window into the brain. Our eyes often provide clues about what’s going on deep inside our heads. They can also provide a window onto the effort that goes into listening. Pupils widen, or dilate, when listening becomes effortful. But pupils are very light sensitive. To counter this limitation, Dr. Herrmann’s lab recently developed a new approach to assess listening effort, which measures eye movements, not pupil dilation. Their research has shown that a reduction in eye movements can be related to listening effort and how difficult individuals are finding speech to comprehend. Eye tracking is a highly accessible technology, even available as mobile, everyday glasses connected to a smart phone.

Being able to diagnose and track hearing challenges earlier, through eye tracking, could provide an easy way to help people seek treatment earlier, potentially avoiding - or at least delaying - a dementia diagnosis.

This is just one example of innovation in Dr. Herrmann’s lab. For a list of his publications click here.

Dr. Herrmann says “Dementia is a disorder that has important life-changing implications for both people living with it, and their families, along with others around them. If dementia can be avoided or at least delayed through proactively treating a modifiable risk factor, this is an important message to amplify.“

To access Baycrest’s World Hearing Awareness Day message, their free online hearing screening tool, and more, click here.