The effects of Kidney-deficiency on auditory cortex metabolism in the elderly: a 1H-MRS study

Objective To investigate the effects of on auditory cortex metabolism in the elderly by using the proton magnetic resonance spectroscopy(1H-MRS).Methods 50 volunteers,including 20 young subjects and 30 older subjects matched for gender,were measured by pure tone audiometry、“kidney-deficiency”-related test and were executed 3.0 T multi-voxel 1H-MRS tests,The ratios of N-acetylaspartate (NAA),choline (Cho) and lactate (Lac) to creatine (Cr) were measured and were compared between the two groups.The t-test analysis were used for statistic process.The relationship between auditory cortex metabolism and the symptom of kidney-deficiency was also analyzed.Resnlts The result of kidney-deficiency-related test and pure tone audiometry revealed that there was significant difference between the two groups and the older subjects had the more severity kidney-deficiency and high-frequency hearing loss (t=6.335、19.558,P＜0.05).The NAA/Cho ratio in the auditory cortex in the older group was significantly lower than that in the younger group (t=2.90,P＜0.05).There were no significant differences between two groups for the ratios of NAA/Cr and Cho/Cr (t=1.415、0.927,P＞0.05).Decrease of the ratio of NAA/Cho in the older group is significantly related with kidneT-deficiency(r=- 0.773,P=0.025).Conclusion kidney-deficiency play a very important role in the hearing loss and reduction of the number of neurons in auditory cortex of older healthy subjects.It suggests one possible underlying mechanism for the speech perception difficulties exhibited by aging adults. Key words: Kidney-deficiency;  Auditory Cortex;  Proton magnetic resonance spectroscopy