High-Frequency Cochlear Amplifier Dysfunction: A Dominating Contribution to the Cognitive-Ear Link.

Jing Yang,Wen Ma,Xinxing Fu,Fuxin Ren,Yao Wang,Xiao Li,Huiquan Wang,Honghao Li,Fei Gao,Siqi Liu,Yue Zhang,Zhihang Qi

doi:10.3389/fnagi.2021.767570

Abstract

Objective: The objective of this study was to investigate the role of the high-frequency cochlear dysfunction in the cognitive-ear link.Methods: Seventy-four presbycusis patients (PC group) and seventy-one age-, sex-, and education-level matched normal hearing controls (NH group) were recruited in this study. Participants underwent a battery of cognitive tests estimated by Montreal Cognitive Assessment (MoCA), Stroop Color-Word Interference Test (Stroop), Symbol Digit Modalities Test (SDMT), Auditory Verbal Learning Test (AVLT), and Trail-Making Test (TMT-A and B), as well as auditory tests including distortion product otoacoustic emission (DPOAE), pure tone (PT) thresholds, and speech reception thresholds (SRT). Data were analyzed using the factor analysis, partial correlation analysis, multiple linear regression models, and mediation models.Results: Distortion product otoacoustic emission detection amplitudes and PT thresholds performed worse gradually from low to high frequencies in both the NH and PC groups. High-frequency DPOAE (H-DPOAE) was significantly correlated with cognitive domains in the PC group (AVLT: r = 0.30, p = 0.04; SDMT: r = 0.36, p = 0.01; Stroop: r = –0.32, p = 0.03; TMT-A: r = –0.40, p = 0.005; TMT-B: r = –0.34, p = 0.02). Multiple linear regression models showed that H-DPOAE predicted cognitive impairment effectively for aspects of memory (R2 = 0.27, 95% CI, 0.03 to 1.55), attention (R2 = 0.32, 95% CI, –6.18 to –0.40), processing speed (R2 = 0.37, 95% CI, 0.20 to 1.64), and executive function (TMT-A: R2 = 0.34, 95% CI, –5.52 to 1.03; TMT-B: R2 = 0.29, 95% CI, –11.30 to –1.12). H-DPOAE directly affected cognition and fully mediated the relationship between pure tone average (PTA)/SRT and cognitive test scores, excluding MoCA.Conclusion: This study has demonstrated that the high-frequency cochlear amplifier dysfunction has a direct predictive effect on the cognitive decline and makes a large contribution to the cognitive-ear link.

Highlights

IntroductionPresbycusis (PC), as the high-incidence chronic disease in the elderly (Lin et al, 2011c), is associated with cognitive decline and dementia (Wayne and Johnsrude, 2015; Livingston et al, 2017, 2020; Loughrey et al, 2018; Jafari et al, 2019; Nixon et al, 2019; Brenowitz et al, 2020; Slade et al, 2020)
The pure tone average (PTA) was associated with cognitive assessments in both PC group and all participants (Figure 2A; detailed data: Table 2)
distortion product otoacoustic emissions (DPOAE) was correlated with cognitive assessments in all participants and was correlated with Symbol Digit Modalities Test (SDMT) and Trail-Making Test (TMT)-A in the PC group

Summary

Introduction

Presbycusis (PC), as the high-incidence chronic disease in the elderly (Lin et al, 2011c), is associated with cognitive decline and dementia (Wayne and Johnsrude, 2015; Livingston et al, 2017, 2020; Loughrey et al, 2018; Jafari et al, 2019; Nixon et al, 2019; Brenowitz et al, 2020; Slade et al, 2020). Recent evidence for a link between cognitive impairment and hearing loss is based on diverse auditory assessments, including the pure tone average (PTA) (Lin et al, 2013; Harrison Bush et al, 2015; Croll et al, 2020), number of distortion product otoacoustic emissions (DPOAE) detected (Belkhiria et al, 2019, 2020), speech reception thresholds (SRT) (Castiglione et al, 2019; Ren et al, 2019), etc. Even though PC most likely results from the degenerative changes of both OHCs and inner hair cells (IHCs) inevitably (Merchant and Nadol, 2010; Wu et al, 2020), whether dysfunction of OHCs or IHCs makes a great sense to the cognitive-ear link in PC remains unclear

Methods

Results

Discussion

Conclusion