Aging effects on auditory and vestibular responses: A longitudinal study

Purpose: To identify age-related changes in the auditory and vestibular sys tems in normal older subjects followed serially over time. Methods: Pure tone hearing levels, speech reception threshold, speech discr imination scores, and vestibule-ocular responses were measured in 57 normal older subjects (mean age, 82) on 5 yearly examinations. Results: There was a significant (P < .001) increase in pure tone threshold averages (about 1 dB per year) and speech reception threshold averages (ab out 2 dB per year), and a significant (P < .001) decrease in discrimination scopes (about 2% per year) over the 5 years of follow-up. There was a sign ificant (P < .05) amplitude-dependent decrease in gain and increase in phas e lead of the vestibule-ocular reflex and a significant (P < .01) decrease in gain of visual-vestibular responses at low frequency sinusoidal stimulat ion over the 5 examinations. Years 1 to 5 differences in individual subject s were significantly (P < .01) correlated across auditory and vestibular te sts, but not between auditory and vestibular tests (P > .01). Conclusion: This is the first longitudinal study to show age-related decrea ses in auditory and vestibular responses in normal older subjects. Because the age-related changes in the auditory system were not correlated with age -related changes in the vestibular system, the 2 systems may age at differe nt rates in the same individual. These changes likely result from degenerat ion in both peripheral and central structures, although age-related changes in the central nervous system probably are more important from a functiona l point of view. Copyright (C) 1999 by W.B. Saunders Company.