Hearing loss is associated with gray matter differences in older adults at risk for and with Alzheimer’s disease

Abstract

Hearing loss in healthy older adults is associated with accelerated brain volume loss; however, little is known about this association in those with or at risk for dementia. Using data from the COMPASS-ND study we investigated associations between hearing loss and hippocampal volume as well as cortical thickness in older adults with subjective cognitive decline (SCD, N=35), mild cognitive impairment (MCI, N=79), and Alzheimer's dementia (AD, N=21). SCD participants with greater pure-tone hearing loss exhibited lower hippocampal volume, a biomarker of dementia. They also showed more cortical thickness in the left superior temporal gyrus and right pars opercularis, suggesting compensatory cortical changes. No significant associations were found in those with cognitive impairment (MCI or AD) who had greater brain atrophy, suggesting that dementia-related neuropathology may supercede any effects of pure-tone hearing loss on brain volume loss. In contrast, greater speech-in-noise reception thresholds were associated with lower cortical thickness bilaterally across much of the cortex in AD. The AD group also showed worse speech-in-noise thresholds compared to the SCD group, suggesting that strong brain atrophy driven by dementia-related neuropathology in AD is associated with hearing problems in noisy environments.

Hearing Screening for Residents in Long-Term Care Homes Who Live with Dementia: A Scoping Review

“…The risk of dementia increases as the degree of threshold hearing loss worsens [ 18 ]. Furthermore, the long-term effects of auditory decline are implicated in changes at a neural level [ 19 ], with evidence suggesting that central auditory dysfunction, as measured on dichotic speech tests [ 20, 21 ], may be a prodromal symptom of Alzheimer’s disease [ 22 ]. Indeed, at the population level, the estimated risk for dementia is reportedly greater for hearing loss than for all other potentially modifiable risk factors at mid-life [ 23 ].…”