Hearing loss has been linked to a number of brain changes, according to research. The auditory system is linked to other parts of the brain, and a lack of auditory input can cause changes in brain structure and function.
Hearing tests and magnetic resonance imaging (MRI) were used by a team of researchers to determine whether hearing impairment is associated with differences in specific brain regions and affects dementia risk. Hearing loss affects more than 60% of adults aged 70 and up in the United States, and it is linked to an increased risk of dementia. The origin of this association is unknown.
To better understand the link, researchers from the University of California, San Diego, and the Kaiser Permanente Washington Health Research Institute used hearing tests and magnetic resonance imaging (MRI) to see if hearing loss is associated with differences in specific brain regions.
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.
Emilie T. Reas
Researchers reported in the November 21, 2023 issue of the Journal of Alzheimer’s Disease that individuals with hearing impairment who participated in this observational study exhibited microstructural differences in auditory areas of the temporal lobe and areas of the frontal cortex involved with speech and language processing, as well as areas involved with executive function.
“These results suggest that hearing impairment may lead to changes in brain areas related to the 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,” said principal investigator Linda K. McEvoy, Ph.D., 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.
“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.”
McEvoy designed and led the study while at UC San Diego, in collaboration with Reas and UC San Diego School of Medicine investigators who gathered data from the Rancho Bernardo Study of Health Aging, a longitudinal cohort study of residents of the Rancho Bernardo suburb in San Diego that launched in 1972. For this analysis, 130 study participants underwent hearing threshold tests in research clinic visits between 2003 and 2005 and subsequently had MRI scans between 2014 and 2016.
According to the study’s findings, hearing loss is associated with regionally specific brain changes that may occur as a result of sensory deprivation and the increased effort required to understand auditory processing stimulations.
“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,” said co-author Emilie T. Reas, Ph.D., assistant professor at the University of California, San Diego School of Medicine.
