Dementia: How hearing loss rewires the brain
In new research, scientists from the University of California, San Diego and the Kaiser Permanente Health Research Institute in Washington have unraveled the complex relationship between hearing loss in older adults and the risk of dementia, revealing that specific brain changes could be the key.
More than 60% of adults over the age of 70 in the United States suffer from hearing loss, and it has long been suspected that this condition could have a link to dementia.
Now, thanks to hearing tests and magnetic resonance imaging (MRI), researchers have identified microstructural differences in specific brain areas related to sound processing and executive functions in those with hearing impairment.
The study, published in the November 21, 2023, issue of the Journal of Alzheimer’s Disease, reveals that people with hearing impairment showed changes in auditory areas of the temporal lobe and in regions of the frontal cortex involved in speech, language and executive function.
Lead researcher Dr. Linda K. McEvoy suggests that these changes could explain the increased risk of dementia associated with hearing loss in older adults.
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“These results suggest that hearing impairment may cause changes in areas of the brain related to sound processing, as well as in areas of the brain related to attention. The extra effort involved in trying to understand sounds can produce changes in the brain that lead to an increased risk of dementia,” Dr. McEvoy said.
Reduce the risk of dementia
Dr. McEvoy also emphasizes the importance of taking preventive measures to reduce the risk of dementia associated with hearing loss. She recommends interventions that reduce the cognitive effort needed to understand speech, such as using closed captioning on television and movies, hearing aids, and visiting quiet places instead of noisy environments.
The experiment involving 130 individuals from the Rancho Bernardo Healthy Aging Study, a longitudinal cohort study launched in 1972, sheds light on the need to protect hearing. Participants underwent hearing threshold testing between 2003 and 2005, and MRI scans between 2014 and 2016.
Emilie T. Reas, co-author of the study and assistant professor at UC San Diego School of Medicine, stresses the importance of hearing protection. “The findings emphasize the importance of protecting hearing by avoiding prolonged exposure to loud sounds, wearing hearing protection when using noisy tools, and reducing the use of ototoxic medications,” said Reas.
These findings could have significant implications for public health, highlighting the need for greater awareness of the relationship between hearing loss and dementia. Research suggests that active hearing protection could be a key strategy to reduce the risk of dementia in the older adult population.
