Central auditory dysfunction in older persons with memory impairment or Alzheimer dementia.

OBJECTIVE: To assess the effect of memory impairment on central auditory function.
DESIGN: Case-control study.
SETTING: The Virginia Merrill Bloedel Hearing Research Center, Seattle, Washington. PARTICIPANTS: The study cohort of 313 volunteers from a dementia surveillance research program comprised 3 groups: (1) controls without memory loss (n = 232); (2) memory-impaired participants with mild memory impairment but without dementia (n = 64); and (3) memory-impaired participants with a dementia diagnosis (n = 17). MAIN OUTCOME MEASURES: Behavioral central auditory tests were the Synthetic Sentence Identification with Ipsilateral Competing Message test, the Dichotic Sentence Identification test, and the Dichotic Digits Test. Memory impairment was indicated by a total score on the Cognitive Ability Screening Instrument of 86 or less, or a total score of 90 or less with a memory subscale score of 10 or less.
RESULTS: The mean score on each central auditory test worsened significantly across the 3 memory groups even after adjustment for age and peripheral hearing status (P<.05); it was poorest in the dementia group and moderately reduced in the memory-impaired group compared with the control group. Heterogeneity of results was noted in all 3 groups.
CONCLUSIONS: Central auditory function was affected by even mild memory impairment. The Dichotic Sentence Identification test in the free report mode was the most sensitive test for the presence of memory impairment. We recommend that central auditory testing be considered in the evaluation of older persons with hearing complaints as part of a comprehensive, individualized program to assist their needs in both the aural rehabilitative and the cognitive domains.