Psychophysical responses to earth-vertical rotations in the elderly
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Date
2012
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Ohio State University. Department of Speech and Hearing Science
Abstract
A growing elderly population is vulnerable to injury or death due to falls. Previous studies documenting the physiologic changes that occur within the vestibular system due to the aging process have shown moderate decreases in caloric and rotational chair responses. Psychophysical testing, which has proven to be critical to understanding the function of the auditory and other sensory systems, has not yet been used to study vestibular function in the elderly. The present study had two goals: to determine if psychophysical thresholds correlate with performance on standard tests of vestibular function, and to determine if older subjects have poorer vestibular psychophysical thresholds than younger subjects.
Eighteen older adults (age range 63-84 years) and thirteen younger adults (age range 20-25 years) participated in the study. Psychophysical testing of vestibular function consisted of rotations about the earth-vertical axis to determine both detection thresholds and discrimination thresholds to angular velocity. Standard tests of vestibular function included sinusoidal harmonic oscillation, steps of velocity, and caloric testing.
On average, older adults performed more poorly on psychophysical tests than their younger counterparts. The best older adults did as well as the best younger subjects on both detection and discrimination tasks, but the worst older adults were far poorer than the worst younger subjects. Psychophysical thresholds did not correspond to performance on rotational chair testing. These results demonstrate that normal older adults have a wider performance range than younger subjects on psychophysical testing. It also indicates that psychophysical testing accesses different information than standard tests of vestibular function. This suggests that psychophysical testing may be an important additional method for measuring balance function in the elderly.