Is vestibular function related to human hippocampal volume?

Abstract

AbstractOBJECTIVESRecent studies implicate the effect of vestibular loss on cognitive decline, including hippocampal volume loss. As hippocampal atrophy is an important biomarker of Alzheimer’s disease, exploring vestibular dysfunction as a risk factor for dementia and its role in hippocampal atrophy is of interest. The main objective is to replicate previous literature on whole-brain and hippocampal volumes in a group with bilateral vestibulopathy (BV).DESIGNHippocampal and whole-brain MRI volumes were compared in adults aged between 55 and 83 years: (1) to substantiate previous literature, participants with BV (n=16) were compared to healthy controls (n=19), (2) to correct for a potential confounding effect of concomitant hearing loss, participants with BV were compared to healthy controls matched on age, sex, and hearing status (n=16), (3) to additionally evaluate the isolated effect of hearing loss on brain structure, participants with sensorineural hearing loss (SNHL; n=15) were compared to healthy controls. Furthermore, (4) to delineate otolith influence on hippocampal volume in a population with preserved vestibular function (healthy controls and SNHL combined; n=34), the role of saccular function was investigated.RESULTSWhole-brain and targeted hippocampal approaches using volumetric and surface-based measures yielded no significant differences in either of three comparisons: (1) BV versus controls, (2) BV versus matched controls, and (3) SNHL versus controls. Binary support vector machines were unable to classify inner ear health status above chance level. (4) Otolith parameters were not associated with hippocampal volume in a population with preserved vestibular function.CONCLUSIONSNo significant differences in whole-brain or hippocampal volume were found when comparing BV participants with healthy controls, nor did concomitant SNHL confound this relationship. Saccular parameters in subjects with preserved vestibular function were not associated with hippocampal volume changes.Key pointsRecent research suggests an association between vestibular function and cognition.Hippocampal atrophy is an important biomarker of Alzheimer’s disease.Bilateral vestibular loss did not modulate hippocampal or whole-brain volume.