[Hearing impairment in patients with mild cognitive impairment and Alzheimer's disease]

To study the relationship between the degrees of peripheral auditory dysfunction and clinical dementia rating (CDR) in the patients with mild cognitive impairment (MCI) and Alzheimer's disease (AD).

Pure-tone thresholds (PT), word recognition scores (WRS), acoustic immittance and auditory brain-stem responses (ABR) were done to evaluate the auditory function in 24 cases of the patients with MCI and in 31 cases of the patients with AD and in 50 subjects of the control group. Clinical dementia rating (CDR) questionnaire was used to define the dementia degree of the subjects.

Twenty-four MCI patients and 31 AD patients were selected, with average age of 72.0 +/- 6. 5 and 73.1+/-7. 5 of whom 70.8% and 67.7% were female separately. There was no significant difference in PTT and WRS between the MCI and AD groups (P > 0.05). In order to ascertain the relationship between hearing level and degree of dementia, all subjects were divided into 4 groups according their hearing loss (PTA <25 dB:0, 25-30 dB:1, 31-35 dB:2, >35 dB:3) to compare their CDR scores (the control:0, MCI:0. 5, mild AD:1). The more the CDR scores have, the more hearing impairment after controlling the confounder factors (Kendalls tau b = - 0.285, P = 0.018). No significant difference was found between the two groups in audiometry reliability, acoustic immittance and ABR (P > 0.05).

The positive relationship was founded the peripheral hearing impairment and the score of CDR questionnaire in less than 0.5 score of CDR groups and mild AD patients.