Hearing loss is linked to dementia

Hearing loss is linked to dementia

summary: Researchers have discovered that hearing loss in older adults is linked to specific changes in the brain, which may increase the risk of dementia.

Using hearing tests and MRI, the study identified differences in microstructure in areas of the brain responsible for auditory processing, speech, and executive function in people with hearing loss. Lead researcher Linda K. McEvoy suggests that these changes may stem from the increased cognitive effort needed to process sounds.

The study emphasizes the importance of hearing protection and early interventions to reduce the risk of dementia.

Key facts:

  1. Hearing loss in older adults is associated with changes in areas of the brain involved in sound processing and executive functions, which may lead to an increased risk of dementia.
  2. The study suggests that cognitive stress in 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 Healthy Aging Study) and was funded by various institutes including the National Institute on Aging and the American Federation for Research on Aging.

source: University of California San Diego

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

To better understand the relationship, a team of researchers at the University of California San Diego and the Kaiser Permanente Health Research Institute in Washington used hearing tests and magnetic resonance imaging (MRI) to determine whether hearing loss was linked to differences in certain areas of the brain.

The study results show that hearing loss is associated with regionally specific brain changes that may occur due to sensory deprivation and increased effort required to comprehend auditory processing stimuli. Credit: Neuroscience News

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

“These findings suggest that hearing loss may lead to changes in areas of the brain associated with processing sounds, as well as in areas of the brain associated with attention,” said lead researcher Linda K. McEvoy, Ph.D., of the School of Public Health and Human Longevity Sciences at the University of California, San Diego. “The extra effort involved in trying to understand sounds may lead to changes in the brain that lead to an increased risk of dementia,” said Professor Emeritus and Senior Research Fellow at Kaiser Permanente Health Research Institute in Washington.

“If so, interventions that help reduce the cognitive effort required to understand speech — such as using subtitles in TV and movies, live captioning or speech-to-text apps, hearing aids, and visiting people in quiet environments rather than noisy spaces — could help.” It is important to protect the brain and reduce the risk of dementia.

McEvoy designed and led the study while at UC San Diego, collaborating with Reese and UC San Diego School of Medicine investigators who collected data from the Rancho Bernardo Healthy Aging Study, a longitudinal cohort study of residents of the Rancho Bernardo suburb of San Diego. which was launched in 1972. For the purposes of this analysis, 130 study participants underwent hearing threshold tests at 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 regionally specific brain changes that may occur due to sensory deprivation and increased effort required to comprehend auditory processing stimuli.

“The results underscore the importance of protecting hearing by avoiding prolonged exposure to loud sounds, wearing hearing protection when using loud instruments and reducing the use of ototoxic medications,” said co-author Emily T. Reyes, Ph.D., Assistant Professor. At the University of California San Diego School of Medicine.

Co-authors include Jacqueline Bergstrom, Donald J. Hagler Jr., David Wing, and Emily T. Reyes, all of UC San Diego.

Financing: This research was funded 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). Archiving and sharing of Rancho Bernardo study data was supported by the National Institute on Aging (AG054067). Data are available through the study website at the following link: knit.ucsd.edu/ranchobernardostudy/.

Disclosures: Donald J. Hagler Jr. as inventor on 2017 U.S. Patent No. 9,568,580, “Identifying White Matter Fiber Trajectories Using Magnetic Resonance Imaging (MRI).” Other authors report no conflicts of interest.

About hearing loss and dementia research news

author: Yadira Galindo
source: University of California San Diego
communication: Yadira Galindo – University of California San Diego
picture: Image credited to Neuroscience News

Original search: Open access.
“Elevated pure-tone thresholds are associated with altered microstructure in cortical areas associated with auditory processing and attentional assignment” by Linda K. McEvoy et al. Journal of Alzheimer’s Disease


a summary

Elevated pure-tone thresholds are associated with altered microstructure in cortical areas related 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 related to advanced brain aging or altered microstructure in regions associated with auditory and cognitive processing.

Methods:

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

results:

PTAs were not associated with brain PAD (β = 0.09; 95% CI: -0.084 to 0.243; p = 0.34). PTAs were associated with decreased restricted diffusion and increased free water diffusion primarily in the temporal and frontal regions of the right hemisphere (restricted diffusion: βs = -0.21 to -0.30; 95% CIs -0.48 to -0.02; ps < 0.03; free water: βs = 0.18 to 0.26; 95% CIs 0.01 to 0.438; ps < 0.04).

Conclusions:

Hearing loss is not associated with advanced brain aging but is associated with differences in brain areas associated with auditory processing and attention control. It is therefore possible that the increased risk of dementia associated with hearing loss arises, in part, from compensatory changes in the brain that may reduce plasticity.

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