Hippocampal atrophy is associated with hearing loss in cognitively normal adults

Ye Ji Shim; Wi Hoon Jung; Alexander J Billig; William Sedley; Jae-Jin Song

doi:10.3389/fnins.2023.1276883

Hippocampal atrophy is associated with hearing loss in cognitively normal adults

Front Neurosci. 2023 Oct 24:17:1276883. doi: 10.3389/fnins.2023.1276883. eCollection 2023.

Authors

Ye Ji Shim^{1

2}, Wi Hoon Jung³, Alexander J Billig⁴, William Sedley⁵, Jae-Jin Song^{2

6}

Affiliations

¹ Department of Otorhinolaryngology-Head and Neck Surgery, Healthcare System Gangnam Center, Seoul National University Hospital, Seoul, Republic of Korea.
² Sensory Organ Research Institute, Seoul National University Medical Research Center, Seoul, Republic of Korea.
³ Department of Psychology, Gachon University, Seongnam, Republic of Korea.
⁴ UCL Ear Institute, University College London, London, United Kingdom.
⁵ Translational and Clinical Research Institute, Newcastle University Medical School, Newcastle upon Tyne, United Kingdom.
⁶ Department of Otorhinolaryngology-Head and Neck Surgery, Seoul National University Bundang Hospital, Seongnam, Republic of Korea.

Abstract

Objectives: A growing body of evidence suggests that age-related hearing loss (HL) is associated with morphological changes of the cerebral cortex, but the results have been drawn from a small amount of data in most studies. The aim of this study is to investigate the correlation between HL and gray matter volume (GMV) in a large number of subjects, strictly controlling for an extensive set of possible biases.

Methods: Medical records of 576 subjects who underwent pure tone audiometry, brain magnetic resonance imaging (MRI), and the Korean Mini-Mental State Exam (K-MMSE) were reviewed. Among them, subjects with normal cognitive function and free of central nervous system disorders or coronary artery disease were included. Outliers were excluded after a sample homogeneity check. In the end, 405 subjects were enrolled. Pure tone hearing thresholds were determined at 0.5, 1, 2, and 4 kHz in the better ear. Enrolled subjects were divided into 3 groups according to pure tone average: normal hearing (NH), mild HL (MHL), and moderate-to-severe HL (MSHL) groups. Using voxel-based morphometry, we evaluated GMV changes that may be associated with HL. Sex, age, total intracranial volume, type of MRI scanner, education level, K-MMSE score, smoking status, and presence of hypertension, diabetes mellitus and dyslipidemia were used as covariates.

Results: A statistically significant negative correlation between the hearing thresholds and GMV of the hippocampus was elucidated. Additionally, in group comparisons, the left hippocampal GMV of the MSHL group was significantly smaller than that of the NH and MHL groups.

Conclusion: Based on the negative correlation between hearing thresholds and hippocampal GMV in cognitively normal old adults, the current study indicates that peripheral deafferentation could be a potential contributing factor to hippocampal atrophy.

Keywords: aging; atrophy; hearing loss; hippocampus; structural neuroimaging.

Grants and funding

The author(s) declare financial support was received for the research, authorship, and/or publication of this article. This work was supported by grants from the Seoul National University Hospital Research Fund (grant No. 04-2020-0700 to YS), from the National Research Foundation of Korea (NRF) grant funded by the Korean government (MSIP) (grant No. NRF-2022R1A2B5B02002139 to J-JS), from the Korea Health Technology R&D Project through the Korea Health Industry Development Institute (KHIDI) funded by the Ministry of Health and Welfare (grant No. HI21C1574 to J-JS), and from Seoul National University Bundang Hospital (grant No. 14-2023-0015 to J-JS). The funding organization had no role in the design or conduct of this research.