Dementia-related hearing loss

Summary: Researchers have found that hearing loss in older adults is associated with specific brain changes, potentially increasing the risk of dementia.

Using hearing tests and MRI scans, the study identified microstructural differences in brain regions responsible for auditory processing, speech and executive function in people with hearing loss. Lead researcher Linda K. McEvoy points out that these changes could come from the increased cognitive effort needed to process sounds.

The study highlights the importance of hearing protection and early interventions to mitigate the risk of dementia.

Highlights:

1. Hearing loss in older adults is linked to changes in brain areas involved in sound processing and executive functions, potentially leading to an increased risk of dementia.
2. The study suggests that the cognitive strain of understanding sounds may contribute to these brain changes, highlighting the need for interventions such as hearing aids and quiet environments.
3. This research is part of a long-term study (Rancho Bernardo Study of Health Aging) and was funded by various institutes, including the National Institute on Aging and the American Federation for Aging Research.

Source: UCSD

Hearing loss affects more than 60 percent of adults aged 70 and older in the United States and is known to be linked to an increased risk of dementia. The reason for this association is not fully understood.

To better understand the link, a team of 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 determine whether hearing loss is associated to differences in specific regions of the brain.

In the November 21, 2023 issue of Journal of Alzheimer’s DiseaseThe researchers reported that individuals enrolled in this observational study and with hearing loss had microstructural differences in auditory areas of the temporal lobe and areas of the frontal cortex involved in speech and language processing, as well as in areas involved in executive function.

“These findings suggest that hearing loss may lead to changes in areas of the brain related to sound processing, as well as areas of the brain related to attention. The extra effort required to try to understand sounds may produce changes in the brain that lead to an increased risk of dementia,” said lead researcher Linda K. McEvoy, Ph.D., Herbert Wertheim School of Public Health and Human Sciences. Human Longevity Sciences from UC San Diego. professor emeritus and principal 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 in television and movies, live or synthesized captioning applications voice, hearing aids and visits in quiet environments instead of noisy environments. spaces – could be important for protecting the brain and reducing the risk of dementia.

McEvoy designed and led the study at UC San Diego, working with investigators from Reas and the UC San Diego School of Medicine who gathered data from the Rancho Bernardo Study of Healthy Aging , a longitudinal cohort study of residents of the San Diego suburb of Rancho Bernardo. which was launched in 1972. For this analysis, 130 study participants underwent hearing threshold tests during research clinic visits between 2003 and 2005 and then underwent MRI scans between 2014 and 2016.

The study results show that hearing loss is associated with region-specific brain changes that may occur due to sensory deprivation and the increased effort required to understand auditory processing stimulations.

“The results highlight 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 the co-author Emilie T. Reas, Ph.D., assistant professor. at the UC San Diego School of Medicine.

Co-authors include: Jaclyn Bergstrom, Donald J. Hagler Jr, David Wing and Emilie T. Reas, all of UC San Diego.

Funding: This research was supported in part by the National Institute on Aging (R00AG057797, R01AG077202, R01AA021187) and the American Federation for Research on Aging/McKnight Foundation (311122-00001). Data collection for the Rancho Bernardo Healthy Aging Study was provided primarily by the National Institutes of Health (HV012160, AA021187, AG028507, AG007181, DK31801, HL034591, HS06726, HL089622). Data archiving and sharing from the Rancho Bernardo study was supported by the National Institute on Aging (AG054067). The data are available on the study website at: knit.ucsd.edu/ranchobernardostudy/.

Disclosures: Donald J. Hagler Jr is listed as an inventor in U.S. Patent 9,568,580, 2017, “Identification of White Matter Fiber Bundles Using Magnetic Resonance Imaging (MRI).” » Other authors report no conflicts of interest.

About this research news on hearing loss and dementia

Author: Yadira Galindo
Source: UCSD
Contact: Yadira Galindo – UCSD
Picture: Image is credited to Neuroscience News

Original research: Free access.
“High pure-tone thresholds are associated with altered microstructure in cortical areas related to auditory processing and attentional allocation” by Linda K. McEvoy et al. Journal of Alzheimer’s Disease

Abstract

Elevated pure-tone thresholds are associated with altered microstructure in cortical areas linked to auditory processing and attentional allocation

Background:

Hearing loss is associated with cognitive decline and increased risk of Alzheimer’s disease, but the basis of this association is not understood.

Objective:

To determine whether hearing loss is associated with advanced brain aging or microstructural alteration in areas involved in auditory and cognitive processing.

Methods :

130 participants (mean 76.4 ± 7.3 years; 65% women) of the Rancho Bernardo Healthy Aging Study underwent a screening audiogram in 2003-2005 and brain magnetic resonance imaging in 2014- 2016. Hearing ability was defined as the average pure tone threshold (PTA) at 500, 1000, 2000, and 4000 Hz in the better-hearing ear. Brain-predicted age difference (Brain-pad) was calculated as the difference between brain-predicted age based on a validated structural imaging biomarker of brain age and chronological age . Regional diffusion measurements in temporal and frontal cortex regions were obtained from diffusion-weighted MRI scans. Linear regression analyzes adjusted for age, sex, education, and health-related measures.

Results:

PTA was not associated with cerebral DBP (β = 0.09; 95% CI: –0.084 to 0.243; p = 0.34). PTAs were associated with reduced restricted diffusion and increased diffusion of free water, mainly in temporal and frontal areas of the right hemisphere (restricted diffusion: βs = –0.21 to –0.30; CI to 95% from –0.48 to –0.02; ps < 0.03; free water: βs = 0.18 to 0.26; 95% CI 0.01 to 0.438; ps < 0.04).

Conclusions:

Hearing loss is not associated with advanced brain aging, but with differences in brain regions involved in auditory processing and attentional control. It is therefore possible that the increased risk of dementia associated with hearing loss arises, in part, from compensatory brain changes that may decrease resilience.