Vestibular function and cortical and sub-cortical alterations in an aging population

Abstract

While it is well known that the vestibular system is responsible for maintaining balance, posture and coordination, there is increasing evidence that it also plays an important role in cognition. Moreover, a growing number of epidemiological studies are demonstrating a link between vestibular dysfunction and cognitive deficits in older adults; however, the exact pathways through which vestibular loss may affect cognition are unknown. In this cross-sectional study, we sought to identify relationships between vestibular function and variation in morphometry in brain structures from structural neuroimaging. We used a subset of 80 participants from the Baltimore Longitudinal Study of Aging, who had both brain MRI and vestibular physiological data acquired during the same visit. Vestibular function was evaluated through the cervical vestibular-evoked myogenic potential (cVEMP). The brain structures of interest that we analyzed were the hippocampus, amygdala, thalamus, caudate nucleus, putamen, insula, entorhinal cortex (ERC), trans-entorhinal cortex (TEC) and perirhinal cortex, as these structures comprise or are connected with the putative “vestibular cortex.” We modeled the volume and shape of these structures as a function of the presence/absence of cVEMP and the cVEMP amplitude, adjusting for age and sex. We observed reduced overall volumes of the hippocampus and the ERC associated with poorer vestibular function. In addition, we also found significant relationships between the shape of the hippocampus (p = 0.0008), amygdala (p = 0.01), thalamus (p = 0.008), caudate nucleus (p = 0.002), putamen (p = 0.02), and ERC-TEC complex (p = 0.008) and vestibular function. These findings provide novel insight into the multiple pathways through which vestibular loss may impact brain structures that are critically involved in spatial memory, navigation and orientation.

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

“…Vestibular information from the semi-circular canals (SCC), otoliths, and nuclei is relayed through the thalamus to the hippocampus, entorhinal cortex, and basal ganglia. The red arrow points toward the ventral lateral nucleus, a putative subfield of the thalamus that receives vestibular input [48]. CAWorks (www.cis.jhu.edu/software/caworks) was used for visualization.…”

“…semicircular canal and/or otolith organs) that contribute to those changes. Bridging these knowledge gaps, novel cross-sectional studies in healthy, older individuals found significant associations between age-related vestibular loss and gross atrophy of the hippocampus [2,48] and the entorhinal cortex [48].…”

“…semicircular canal and/or otolith organs) that contribute to those changes. Bridging these knowledge gaps, novel cross-sectional studies in healthy, older individuals found significant associations between age-related vestibular loss and gross gray matter loss of the hippocampus [2,48] and the entorhinal cortex [48], as well as shape changes in the hippocampus, amygdala, caudate nucleus, putamen, thalamus, entorhinal cortex, and the entorhinal-transentorhinal cortical complex [48].…”

Visuo-postural dependency index (VPDI) in human postural control

“…Currently, it is unclear the rate of progression and how this reorganization is implemented. However, this idea is supported by compounding evidence emerging from neuroimaging studies showing that the age-related effects across sensory systems differ [73,74]. For example, deterioration of vestibular substrate has been welldocumented to be linked to volume reduction of vestibular nuclei in the brainstem and reduction of cerebellar volume [73].…”

“…However, this idea is supported by compounding evidence emerging from neuroimaging studies showing that the age-related effects across sensory systems differ [73,74]. For example, deterioration of vestibular substrate has been welldocumented to be linked to volume reduction of vestibular nuclei in the brainstem and reduction of cerebellar volume [73]. On the other hand, evidence of age-related changes in the visual cortex is primarily associated with functional aspects of neurons and neuronal communication in the visual system [70].…”