Graduation Year

2020

Document Type

Dissertation

Degree

Ph.D.

Degree Name

Doctor of Philosophy (Ph.D.)

Degree Granting Department

Communication Sciences and Disorders

Major Professor

Jennifer J. Lister, Ph.D.

Co-Major Professor

Richard A. Roberts, Ph.D.

Committee Member

Jerri D. Edwards, Ph.D.

Committee Member

Theresa H. Chisolm, Ph.D.

Committee Member

Ross Andel, Ph.D.

Keywords

Aging, Cognition, Vestibular function

Abstract

This study examined oculomotor and vestibular function in young adults, cognitively normal older adults (CNOA), and older adults with MCI. Oculomotor and vestibular function were assessed using videonystagmography (VNG), vestibular evoked myogenic potentials (VEMPs), the modified Clinical Test of Sensory Integration and Balance (mCTSIB), and the Fukuda Stepping test. Forty-two participants comprised three groups (young adults, n = 15; CNOA, n = 13; MCI, n = 14). The Montreal Cognitive Assessment ([MoCA]; Nasreddine et al., 2005) was used to assess cognitive status, and a MCI diagnosis was confirmed using standardized neuropsychological testing and a physician’s exam. MANOVA was calculated to compare young and older adults with and without MCI on oculomotor and vestibular function. Chi-square analysis was calculated to examine the proportion of clinically significant unilateral weakness among groups. Results indicated the young adult group showed shorter saccade latencies than either CNOA or MCI groups. The MCI group also showed both a higher mean unilateral caloric weakness and a higher occurrence of unilateral caloric weakness than either young adult or CNOA groups. The young adult group showed larger P1-N1 amplitudes than either CNOA or MCI groups for cervical VEMPs. There were no additional group differences on remaining oculomotor or vestibular measures. These results indicate older adults with MCI may show vestibular asymmetry assessed using bithermal caloric irrigation, however, these findings are not conclusive. Functional balance and spatial ability are known to be impaired in older adults with cognitive decline. The purpose of this study was to examine the relationships between oculomotor and vestibular function, functional balance, and spatial ability in young adults and older adults with and without MCI. Oculomotor and vestibular function, and cognitive status were assessed using screening and diagnostic measures. This data was collected and described in the previous study. Functional balance was assessed using the Timed Up and Go (Podsiadlo & Richardson, 1991) and Functional Reach tests (Duncan et al., 1990). Spatial ability was assessed using the Hidden Goal Task (Kalová et al., 2005), a computerized test of spatial navigation. Forty-two participants comprised three groups (young adult, n = 15; CNOA, n = 13; MCI, n = 14). MANOVA was calculated to examine group differences on functional balance and spatial ability. Two multiple linear regressions were also calculated to examine the contribution of oculomotor or vestibular function to functional balance and spatial ability. The young adult group showed better performance on the Functional Reach and Timed Up and Go tests compared to MCI group, ps < .005, however, there were no differences between young adult and CNOA groups, ps > .114. The young adult group also showed better performance on the Hidden Goal Task compared to either CNOA or MCI groups, ps < .042. Results showed VOR and VSR were significantly associated with functional balance and spatial ability, respectively. These results suggest VOR and VSR assessment may be considered as part of routine non-invasive battery for detecting signs and symptoms linked to cognitive decline, such as reduced functional balance and spatial ability.

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