Abstract
A growing body of literature has demonstrated that dementia and hearing loss are interrelated. Recent interest in dementia research has expanded to brain imaging analyses with auditory function. The aim of this study was to investigate the link between hearing ability, which was assessed using pure-tone audiometry, and the volume of brain regions, specifically the hippocampus, entorhinal cortex, Heschl’s gyrus, and total gray matter, using Freesurfer software and T1-weighted brain magnetic resonance imaging. The data for 2082 samples (age range = 40–89 years) were extracted from a population-based cohort of community dwellers. Hearing-impaired individuals showed significantly smaller hippocampal volumes compared with their non-hearing-impaired counterparts for all auditory frequency ranges. In addition, a correlational analysis showed a significant dose-response relationship for hearing ability and hippocampal volume after adjusting for potential confounding factors so that the more degraded the peripheral hearing was, the smaller the hippocampal volume was. This association was consistent through the auditory frequency range. The volume of the entorhinal cortex, right Heschl’s gyrus and total gray matter did not correlate with hearing level at any frequency. The volume of the left Heschl’s gyrus showed a significant relationship with the hearing levels for some auditory frequencies. The current results suggested that the presence of hearing loss after middle age could be a modifier of hippocampal atrophy.
Highlights
The number of studies investigating the interrelationship of dementia and hearing loss has increased rapidly
In this study, we examined the detailed relationships between hearing ability, which was assessed by pure-tone audiometry, and hippocampal volume, which was estimated by T1-weighted magnetic resonance imaging (MRI) using Freesurfer software in 2082 community-dwelling volunteers who were 40–89 years old
Hearing impairment was defined as a pure-tone average. PTA low (PTA) greater than 25 dB
Summary
The number of studies investigating the interrelationship of dementia and hearing loss has increased rapidly. Systematic reviews and meta-analyses of the association between hearing loss and cognitive function, cognitive impairment, and dementia were successively published in 2017 (Loughrey et al, 2017; Thomson et al, 2017; Zheng et al, 2017). Loughrey et al (2017) found. Hippocampal Volume and Hearing a significant association between age-related hearing loss and 10 cognitive domains, such as global cognition, executive function, and episodic memory, in 26 cross-sectional studies involving 15,620 participants and 1185 records. Other systematic reviews had different inclusion criteria, analytical estimates have suggested that hearing loss might be a biomarker and modifiable risk factor for cognitive impairments and dementia in older adults
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