In this project, Dr Brian Allman at the University of Western Ontario, Canada, investigates whether brain inflammation connects hearing loss with dementia, and how hearing loss may worsen age-related cognitive impairments.
Project start date: January 2020
Project end date: December 2023
Read about the project outcomes here.
About the project
Recent evidence shows there’s a link between dementia and hearing loss, but little is understood about how they’re connected. Evidence from previous research suggests that inflammation of nerve cells in the brain (‘neuroinflammation’) occurs with both exposure to loud noise (loud enough to cause hearing loss) and the decline in cognitive abilities that occurs with aging.
It’s possible that neuroinflammation is a link between the two conditions – but more research is needed.
How it works
First, researchers will study the brain changes that occur during noise-induced hearing loss and that may speed up the cognitive impairments that occur in old age. Secondly, they will investigate how hearing loss may worsen these cognitive problems in a way that is specific to Alzheimer’s disease.
To do this, researchers will expose rats to loud noise when they’re young and, as they age, analyse brain structures and pathology, conduct non-invasive brain imaging and measure their learning and memory behaviours.
They’ll study both normal rats and those whose genetics have been modified so that they are susceptible to developing brain damage that is consistent with people suffering from Alzheimer’s disease.
How will this research benefit people at risk of hearing loss?
This research will provide one of the first investigations into the biological processes that link hearing loss, age-related cognitive decline, brain inflammation and Alzheimer’s-related pathology.
Ultimately, this knowledge may lead to the development of treatments that can be used in people, such as drugs aimed at reducing the risk of dementia associated with hearing loss, which could have considerable future clinical implications for millions of people.
What we’ve learned so far
The researchers found that noise exposure can exacerbate age-related cognitive decline. However, the extent of cognitive impairment was not linked to the degree of hearing loss.
This finding could have significant implications, as researchers and clinicians would not likely be able to reliably predict who may go on to experience cognitive impairments later in life based simply on the degree of hearing loss they experienced from noise exposure earlier in adulthood.
About the researcher
Dr Brian Allman is an Associate Professor at the University of Western Ontario, Canada. He was awarded an RNID Discovery Research Grant for this project in 2019, which was co-funded in partnership with Alzheimer’s Research UK.