Hearing difficulties linked to the onset of dementia

Key points:

• Approximately 3.6 million people have some level of hearing loss in Australia

• Over 1.3 million people live with a hearing condition that could have been prevented

• Hearing loss is known to be related to an increased risk of dementia, however, the reason for this association is not entirely known

The strong association between hearing loss and the onset of dementia has prompted a new study, published in the Journal of Alzheimer’s Disease.

Researchers from the University of California San Diego and Kaiser Permanente Washington Health Research Institute used hearing tests and magnetic resonance imaging brain scans to determine whether a hearing impairment impacted certain areas of the brain.

They found that hearing loss was associated with regions of the brain that are responsible for speech and language processing, as well as areas involved with executive function — which refers to attention, memory and the ability to plan.

Principal investigator Linda McEvoy, PhD, said the association between hearing loss and dementia was possibly related to the extra effort it takes to process sounds for people who live with hearing loss.

“The extra effort involved with trying to understand sounds may produce changes in the brain that lead to increased risk of dementia,” the UC San Diego Herbert Wertheim School of Public Health and Human Longevity Science professor emeritus and senior investigator at the Kaiser Permanente Washington Health Research Institute said.

“If so, interventions that help reduce the cognitive effort required to understand speech — such as the use of subtitles on television and movies, live captioning or speech-to-text apps, hearing aids and visiting with people in quiet environments instead of noisy spaces — could be important for protecting the brain and reduce the risk of dementia.”

The analysis involved 130 study participants who took part in hearing threshold tests in research clinic visits between 2003 and 2005 and subsequently had MRI scans between 2014 and 2016.

The results of the study show that hearing impairment is associated with regionally specific brain changes that may occur due to sensory deprivation and the strain of processing sounds that are harder to detect.

Co-author Emilie Reas, PhD, assistant professor at the UC San Diego School of Medicine, said the new study is a testament to the importance of hearing protection throughout life.

“The findings emphasise the importance of protecting one’s hearing by avoiding prolonged exposure to loud sounds, wearing hearing protection when using loud tools and reducing the use of ototoxic medications,” she said.

The Australian Department of Health and Aged Care has estimated that as Australia’s population ages, the number of people with a hearing impairment is expected to double to an estimated 7.8 million people in 2060.

Age is a contributing factor to both the onset of dementia and the progressive development of hearing loss. Hearing loss increases from about half of those aged 60 to 70, to 70 percent of those aged 70 or over and 80 percent of those aged 80 and over.

For more information about hearing loss in Australia, including ear health management and detection, please visit the Know Your Noise website or contact 02 9412 6800 to learn more.

Do you find it easier to watch television with subtitles on? Let the team at Talking Aged Care know your thoughts and subscribe to the newsletter for more free up-to-date information.