Hearing loss affects more than 60% of adults aged 70 and older in the United States and is known to be related to an increased risk of dementia. However, the reason for this link is not fully understood. Now, researchers at the University of California, San Diego (UCSD), and Kaiser Permanente Washington Health Research Institute have discovered that increased dementia risk associated with hearing impairment may come from compensatory brain changes.
Their findings are published in the Journal of Alzheimer’s Disease in an article titled, “Elevated Pure Tone Thresholds Are Associated with Altered Microstructure in Cortical Areas Related to Auditory Processing and Attentional Allocation.”
“Hearing loss is associated with cognitive decline and increased risk for Alzheimer’s disease, but the basis of this association is not understood,” wrote the researchers. To better understand the connection, the researchers employed hearing tests and magnetic resonance imaging to determine whether hearing impairment is associated with differences in specific brain regions.
The results of the study show that hearing impairment is associated with regionally specific brain changes that may occur due to sensory deprivation and to the increased effort required to understand auditory processing stimulations.
“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,” explained principal investigator Linda K. McEvoy, PhD, UCSD Herbert Wertheim School of Public Health and Human Longevity Science professor emeritus and senior investigator at the Kaiser Permanente Washington Health Research Institute.
The researchers concluded hearing impairment is not associated with advanced brain aging but is associated with differences in brain regions involved with auditory processing and attentional control. It is thus possible that increased dementia risk associated with hearing impairment arises, in part, from compensatory brain changes that may decrease resilience.
“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, PhD, assistant professor at the UCSD School of Medicine.