Linking vestibular function and sub-cortical grey matter volume changes in a longitudinal study of aging adults

Original Research Manuscript

Linking vestibular function and sub-cortical grey matter volume changes in a longitudinal study of aging adults

Aging (Healthy and Neurodegenerative Disorders) Language Functional or Resting State MRI Early Life Neurodevelopment (Healthy and Neurodevelopmental Disorders)

Abstract

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Correspondence dpadova1@jhu.edu

Linking vestibular function and sub-cortical grey matter volume changes in a longitudinal study of aging adults

Dominic Padovaa, J. Tilak Ratnanatherb, Qian-Li Xuec,d, Susan M. Resnicke, Yuri Agrawala 

a Department of Otolaryngology–Head and Neck Surgery, Johns Hopkins University School of Medicine, Baltimore, MD, USA 

b Center for Imaging Science and Institute for Computational Medicine, Department of Biomedical Engineering, The Johns Hopkins University, Baltimore, MD, USA  

c Department of Medicine Division of Geriatric Medicine and Gerontology, School of Medicine, Johns Hopkins University, Baltimore, Maryland, USA

d Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA

e Laboratory of Behavioral Neuroscience, National Institute on Aging, National Institutes of Health, Baltimore, MD, United States of America 

Comprehensive Summary

Humans rely on their vestibular, or inner ear balance, system to manage everyday life. In addition to sensing head motion and head position with respect to gravity, the vestibular system helps to maintain balance and gaze stability. Furthermore, evidence is mounting that vestibular function is linked to structural changes in the central nervous system (CNS). Yet, the exact processes by which vestibular function alters brain structural integrity is unclear. One possible mechanism is that progressive vestibular deafferentation results in neurodegeneration of structures that receive vestibular input. In support of this putative mechanism, recent studies report the association of vestibular impairment with volume loss of brain areas that receive vestibular information, specifically the hippocampus and entorhinal cortex, in older adults. This present work investigates the extent over time to which age-related vestibular loss contributes to volume reduction of four brain regions that receive vestibular input: the hippocampus, entorhinal cortex, thalamus, and basal ganglia. Using data from a cohort of healthy, older adults between 2013 and 2017 from the Baltimore Longitudinal Study of Aging, we assessed regional brain volume as a function of vestibular function, while accounting for common confounds of brain volume change (e.g., age, sex, head size). We found that poor vestibular function is associated with significantly reduced volumes of the thalamus, basal ganglia, and left hippocampus. Notably, this study is one of the first to demonstrate relationships between age-related vestibular loss and gray matter loss in brain regions that receive vestibular input. Further research is needed to understand in greater detail the observed link between vestibular function and CNS structure. Which brain areas are impacted by age-related vestibular loss? How and in what sequence are they impacted? As the world’s aging population—and the prevalence of age-related vestibular impairment—increases, answering questions like these becomes increasingly important. One day, these answers will provide targets for preemptive interventions, like physical pre-habilitation, to stave off adverse changes in brain structure before they occur and progress towards clinical significance.