Hearing loss impacts about a third of older adults and can lead to depression, social isolation, loneliness, and even safety issues when driving or walking. It’s also been shown to increase dementia risk, and a new study may have learned more about why.
Research recently published in the Journal of Alzheimer’s Disease investigated whether hearing loss is due to advanced brain aging or changes within the brain’s structure. Using hearing tests and brain scans, the researchers found that with hearing loss, there were differences in areas of the brain that handle auditory processing and attentional control. The team says this suggests that the changes come from the brain working harder to decipher sounds.
Dr. Linda McEvoy, the study’s lead researcher and senior investigator at the Kaiser Permanente Washington Health Research Institute, says, “These results suggest that hearing impairment may lead to changes in brain areas related to processing of sounds, as well as in areas of the brain that are related to attention. The extra effort involved with trying to understand sounds may produce changes in the brain that lead to increased risk of dementia.
“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.”
This idea supports other research that has found hearing aids and cochlear implant use are linked with a lower risk of dementia.
In this study, researchers used data from the Rancho Bernardo Study of Health Aging, which has tracked the long-term health of residents of San Diego’s Rancho Bernardo suburb since 1972. One hundred thirty of these participants had hearing tests done between 2003 and 2005 and then had MRI scans between 2014 and 2016.
The tests showed that participants with hearing loss had microstructural differences in the auditory areas within the temporal lobe, in areas of the frontal cortex linked with speech and language processing, and areas involved in executive function. The researchers believe these changes are linked with sensory deprivation and the extra effort involved in auditory processing.
They also believe their study is a good reason for people to safeguard their hearing as best they can.
Dr. Emilie Reas, study co-author and assistant professor at the UC San Diego School of Medicine, says, “The findings emphasize 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.”