Hearing aids can help slow the brain aging process in adults with mild cognitive impairment, a small study of brain scans suggests.
Researchers from the University of California, Los Angeles, said their study found that while hearing loss can accelerate the decline in brain metabolism in cognitive impairment, hearing aids may ameliorate this acceleration.
They presented results simultaneously at the 2024 Society of Nuclear Medicine and Molecular Imaging annual meeting in Toronto from 8 to 11 June 2024 and in the Journal of Nuclear Medicine on 9 June.
The study found those who used hearing aids experienced less decline in brain metabolism than those with untreated hearing loss, especially in the frontal regions of their cortex which are important for executive functions and are known to decline with aging.
“These results suggest that while hearing loss can accelerate the decline in brain metabolism that occurs in people suffering from mild cognitive impairment, this acceleration may be largely mitigated through the use of hearing aids,” said lead author, psychobiology undergraduate student Ms Natalie Quilala.
While the impact of hearing loss and use of hearing aids on the risk of developing dementia had been studied previously, the cross-comparison between people with hearing loss and those with hearing aids and changes in brain metabolism over time had not been elucidated, she added.
“In this study, we report findings using longitudinal F-FDG PET scan data and neuropsychological assessments among subjects diagnosed with hearing loss, with and without the use of hearing aids,” Quilala said.
From the Alzheimer’s Disease Neuroimaging Initiative database, researchers identified 1,647 people with amnestic mild cognitive impairment. Of these, 351 were identified as having hearing impairment. Subjects were further narrowed by assessing those whose only sensory impairment was hearing loss and those with multiple annual FDG-PET brain scans archived after baseline.
The remaining 31 were categorised into groups with untreated hearing loss, hearing loss treated with hearing aids, and a demographically matched control group with no diagnosed hearing impairment. Brain metabolism in 47 standardised volumes of interest from each of the FDG-PET scans was quantified and compared within and between-groups in rate-of-change analyses.
Faster decline in untreated hearing loss group
The hearing loss group demonstrated significant annual metabolic decline in six frontal cortical regions and two superior temporal regions. The control group, however, exhibited significant decline in only two superior temporal regions, likely reflective of the presence of an early neurodegenerative process, but in none of the frontal cortical regions.
“Strikingly, the hearing aid group did not experience significant annual metabolic decline in any frontal cortical region,” researchers noted. “Furthermore, direct statistical comparison of rates of decline in difference-of-differences analyses demonstrated that multiple frontal cortical regions declined significantly faster in the untreated hearing loss group than in the group treated with hearing aids, and no frontal cortical region declined significantly faster in the hearing aid group than in the control group.”
Specific details included that over one year, the most significant differential metabolic decline occurred in the left superior frontal gyrus when comparing the control group with the untreated hearing loss group. The hearing aids group against the control group yielded a significant differential decline in left superior frontal gyrus as well, while the hearing loss group declined 1.5 times faster than the hearing aids group.
After two years, the untreated hearing loss group had significant declines against the control group in the right mid-frontal gyrus, the right posterior inferior frontal gyrus, and left inferior frontal gyrus. In contrast, during the same period of time, the hearing aids group had no significant decline in metabolic rate in these or any of the other 47 standardised volumes of interest examined.
Researchers concluded: “The use of hearing aids by subjects with mild cognitive impairment at baseline was associated with less cerebral metabolic decline than was observed in subjects with untreated hearing loss relative to control subjects with no diagnosed hearing loss, primarily in frontal cortical regions that are known to decline with normal aging.
“These results suggest that while hearing loss may accelerate the aging process occurring in cerebral metabolism, this acceleration may be ameliorated by the use of hearing aids.”
Other researchers in the team were physician-scientist Dr Daniel Silverman, Mr Stephen Liu and clinical research associate Ms Helen Struble.
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