HIDDEN HEARING LOSS AND COGNITIVE MEASURES IN HEALTHY ELDERS

Abstract

Epidemiological evidence shows an association between presbycusis or age-related hearing loss and cognitive decline in elderly people. Presbycusis subjects with audiometric hearing thresholds (PTA) worse than 40 dB are more likely to develop cognitive decline. The mechanisms of this epidemiological association are unknown. Here we propose that hidden hearing loss (HHL), that is the loss of auditory-nerve neurons without alterations at the audiometric thresholds, is an important factor linking presbycusis and cognitive decline. HHL can be assessed using supra-thresholds auditory brainstem responses (ABR). Analyze supra-thresholds ABR responses and cognitive measures in healthy elders. 52 Persons from the ANDES study ≥65 years without dementia (MMSE>24) with normal hearing thresholds (PTA<20dB, n=13), with mild (PTA: 20–39dB, n=29) or moderate presbycusis (PTA≥40dB, n=10), were evaluated using a comprehensive neuropsychological assessment and with the self-reported questionnaire of hearing handicap inventory for the elderly (HHIE). Amplitudes and latencies of ABR waves I and V were obtained at supra-thresholds levels. The ratio between wave I/V was computed as a measure of HHL. These ABR variables were analyzed and correlated with cognitive tests. Those with moderate presbycusis had significant higher scores in the HHIE (F(2)=5.80, p=0.005). The MMSE score correlated with the amplitude (r=0.40, p=0.006) and latency (r=-0.38, p=0.009) of wave I, and the amplitude ratio (waves I/V) (r=0.38, p=0.009) of the right ear. The Boston test correlated with bilateral amplitude ratios (wave I/V) of wave I (right: r=0.34, p=0.023; left: r=0.37, p=0.013). The Wisconsin card sorting test correlated with the amplitude of right ABR waves I (r=0.30, p=0.03) and V (r=0.32, p=0.03). The Corsi test with (r=0.33, p=0.28) and without (r=0.33, P=0.03) noise correlated with the amplitude ratio of wave I/V in the left ear. Auditory nerve supra-thresholds responses correlate with several cognitive measures in healthy elderly subjects. These preliminary results should be confirmed with a larger sample of presbycusis patients. Funded by Proyecto Anillo ACT1403, Fondecyt 1140423, and Fondecyt 1161155.