Auditory Function Testing for Types of Dementia: Systematic Reviews and Meta-Analysis

It is acknowledged that there is a negative relationship between dementia and auditory function in older adults. This study conducted a systematic review and meta-analysis based on the data of audiologic testings from patients with neurodegenerative diseases in terms of auditory eventrelated potentials and central auditory processing tests, while focusing on Alzheimer’s disease (AD), dementia with Lewy bodies (DLB), and Parkinson’s disease dementia (PDD). A total of 34765 articles were retrieved from the seven electronic databases. After being screened by Participants, Index test, Control, Outcomes, Study design (PICOS) criteria, 129 articles for AD were included and then 72 articles were applied to the meta-analysis. However, five and six articles were systematically reviewed for the auditory functions of DLB and PDD, respectively, due to a small number of articles. The results of meta-analysis showed a significant difference between patients with AD and age-matched normal subjects, for N200 and P300 latency, P300 amplitude, and the behavioral central auditory processing tests, although there was a high heterogeneity. On the other hand, the systematic review indicated that the results of mismatch negativity test might distinguish auditory performance of DLB patients from that of PDD. Furthermore, for P300 amplitude, anterior to posterior distribution of brain resulted in meaningful difference of auditory function between AD and DLB patients. In sum, current review study suggests that lesion and degree of auditory (dys)function may be different depending on the type of dementia, although future research should be followed.