Study finds subtle brain alterations associated with hearing loss

The link between hearing thresholds and brain changes revealed.

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Hearing loss affects over 60% of adults aged 70 and older in the U.S. and is linked to a higher risk of dementia. To understand this connection, researchers from the University of California San Diego and Kaiser Permanente Washington Health Research Institute conducted hearing tests and MRI scans.

In the November 21, 2023, issue of the Journal of Alzheimer’s Disease, they revealed that participants with hearing impairment in the study showed microstructural differences in the auditory areas of the temporal lobe and areas of the frontal cortex related to speech, language processing, and executive function.

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 said, “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 interventions can reduce the cognitive effort needed for understanding speech, such as using subtitles, live captions, hearing aids, and choosing quiet environments, it could protect the brain and lower the risk of dementia.

The study, led by McEvoy in collaboration with researchers from UC San Diego, analyzed data from the Rancho Bernardo Study of Health Aging. Among 130 participants who underwent hearing tests between 2003 and 2005 and MRI scans between 2014 and 2016, the results revealed that hearing impairment is linked to specific brain changes, possibly due to sensory deprivation and increased effort in auditory processing.

Co-author Emilie T. Reas, Ph.D., assistant professor at the UC San Diego School of Medicine, said, “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.”

The study contributes valuable insights into the intricate relationship between hearing loss and subtle brain changes. By identifying specific brain regions affected by hearing impairment, the research opens avenues for targeted interventions that may enhance the quality of life for individuals with hearing loss and potentially mitigate the risk of dementia associated with this prevalent condition.

Journal reference:

  1. Jacobson, Mark W., McEvoy, Linda K., et al., Elevated Pure Tone Thresholds Are Associated with Altered Microstructure in Cortical Areas Related to Auditory Processing and Attentional Allocation. Journal of Alzheimer’s Disease. DOI: 10.3233/JAD-230767.

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