Longitudinal Changes in Auditory and Cognitive Function in Middle-Aged and Older Adults.

Purpose This article aimed to document longitudinal changes in auditory function, including measures of temporal processing, and to examine the associations between observed changes in auditory and cognitive function in middle-aged and older adults. Method This was a prospective longitudinal study of 98 adults (66 women) with baseline ages ranging from 40 to 85 years. The mean interval between T1 baseline and T2 follow-up measurements was 8.8 years with a range of 7-11 years. Measures of hearing threshold, gap detection, and auditory temporal-order identification were completed at T1 and T2. Cognitive measures completed at T1 and T2 were the 13 scales of the Wechsler Adult Intelligence Scale-Third Edition. Three approaches were taken to analyze these data: (a) examination of changes over time in group performance, (b) correlations and slopes between auditory and cognitive measures to examine concomitant rates of decline over the 9-year T1-to-T2 period, and (c) regression analyses examining associations between auditory performance at T1 and cognitive performance 9 years later at T2. Results For the group data, there were significant declines in hearing loss, gap-detection thresholds at one frequency, and process-type measures of cognitive function from T1 to T2 matching the trends in the baseline cross-sectional data. Regression analyses of the longitudinal data revealed the strongest connection between auditory temporal-order processing and cognitive processing typically explaining 10%-15% of the variance. Conclusions A significant amount of variance in rates of cognitive decline, T1 to T2, and subsequent cognitive performance (T2) was explained by measures of auditory function. Although hearing loss occasionally emerged as a significant factor, auditory temporal-order identification emerged much more frequently as the auditory measure most strongly associated with cognitive function.