A preliminary study on the correlation between auditory function and cognitive function in the elderly

Abstract

Objective:To evaluate the cognitive function of patients with presbycusis, and to explore the relationship among age, hearing loss, speech recognition ability and cognitive function. Method:A total of 131 elder participated in this study. Based on hearing threshold, all participants were divided into the elderly hearing loss group（66 cases） and the control group（65 cases with normal hearing）. ① The pure tone audiometry test was completed to obtain the average hearing threshold of 0.5, 1, 2, and 4 kHz; ② The single-syllable vocabulary in Mandarin Speech Test Materials was used to test the maximum speech recognition rate and the speech recognition rate at 60 dB HL in a quiet environment about the better ear; ③ Chinese version of the Mini-mental State Examination（MMSE） was used to assess the subject's cognitive function; ④ Use spearman correlation coefficient to analyze the correlation between age, average hearing threshold, maximum speech recognition rate and the MMSE score; ⑤ Use GLM to analyze the effects of gender, deafness time, and education level on the cognitive function in presbycusis patients. Result:① The proportion of mild cognitive dysfunction（<27 points）（16.7%） in the elderly hearing loss group was higher than the control group（10.8%）, but there was no significant difference（P>0.05）; ②The MMSE score decreased with age（P<0.05）, and there was a significant correlation between MMSE score and age（the control group: r=-0.424, P=0.000; the elderly hearing loss group: r=-0.277, P=0.024）; ③There was a significant difference in MMSE scores between groups with different average hearing threshold levels（P<0.05）, and there was a significant correlation between the MMSE score and the average hearing threshold in the elderly hearing loss group（r=-0.375, P<0.01）; ④The MMSE score of the elderly hearing loss group with a low speech recognition rate at 60 dB HL（<50%） was significantly lower than the group with a high speech recognition rate（≥50%）, and there was a significant correlation between MMSE score and maximum speech recognition rate（r=0.402, P=0.001）; ⑤The average age and hearing threshold of the MCI in the elderly hearing loss group were significantly higher than the normal cognitive function group（27-30 points）（P<0.05）, and the average maximum speech recognition rate was significantly lower than the normal cognitive function group（P<0.05）; ⑥Analyzed by the GLM, the deafness time and education level have significant effects on MMSE scores（β=-0.066, t=-2.98, P<0.01; β=0.286 9, t=2.39, P<0.05）, but gender have no significant effect on MMSE scores（β=0.277, t=1.46, P=0.143）. Conclusion:The age, hearing loss and speech recognition ability of presbycusis patients was significantly correlated with cognitive function. The incidence rate of MCI in presbycusis patients is higher than that in elderly normal hearing subjects. Deafness time is a risk factor of mild cognitive impairment, while education is a protective factor.