New dementia theory grapples with hearing loss

Researchers at Newcastle University suggest a possible link between Alzheimer’s disease, the temporal lobe and hearing loss.

Monika Warzecha 2 minute read September 22, 2020
Hearing dementia

Researchers looked at existing studies of dementia and hearing loss. Getty

A new theory suggests a possible link between Alzheimer’s disease, an important memory centre in the brain, and hearing loss.

Reasearchers with Newcastle University in the U.K. published an article in Neuron, a neuroscience journal, in early September, looking at existing research into hearing and Alzheimer’s. One study suggested an estimated nine per cent of cases of dementia can be attributed to hearing loss.

“The challenge has been to explain how a disorder of the ear can lead to a degenerative problem in the brain,” says Tim Griffiths, from Newcastle University’s Faculty of Medical Sciences. “We suggest a new theory based on how we use what is generally considered to be the memory system in the brain when we have difficulty listening in real-world environments.”

The challenge has been to explain how a disorder of the ear can lead to a degenerative problem in the brain

The researchers looked into three main considerations: “a common underlying cause for hearing loss and dementia; lack of sound-related input leading to brain shrinking; and cognitive impairment resulting in people having to engage more brain resources to compensate for hearing loss, which then become unavailable for other tasks.”

Studying findings from a variety of studies of dementia in humans and animals, the researchers focused on the temporal lobe, the part of the brain crucial to memory and also plays a role in processing sound.

“This memory system engaged in difficult listening is the most common site for the onset of Alzheimer’s disease,” says Newcastle University’s Will Sedley. “We propose that altered activity in the memory system caused by hearing loss and the Alzheimer’s disease process trigger each other.”

The researchers hope new studies will focus on testing the theory by tracking hearing impairment.