The Use of Mismatch Negativity in Conjunction with Neuropsychological Tests to Discriminate Alzheimer's Dementia, Mild Cognitive Impairment and Healthy Aging.

Abstract

Introduction: Alzheimer's dementia (AD) is the most common type of dementia and it is important to detect AD by an appropriately cheap and non-invasive method in the mild cognitive impairment (MCI) phase, which is accepted as the prodromal phase of AD. We aimed to investigate whether AD patients, amnestic MCI (aMCI) patients, and healthy controls (HCs) could be distinguished from each other by using mismatch negativity (MMN) together with neuropsychological tests.

Methods: Twenty-one individuals with mild AD, 26 with aMCI, and 18 HCs matched for age, sex, and education were included. Sociodemographic data, neuropsychological tests, Basic Activities of Daily Living (BADL) and Instrumental Activities of Daily Living (IADL) scores, and MMN parameters acquired using an auditory oddball paradigm with an interstimulus interval of 1 second were evaluated for all three groups.

Results: There was no difference in terms of MMN latencies but frontal MMN amplitude was significantly lower in AD patients compared to the aMCI and HC groups. Linear regression analysis revealed that IADL scores were predicted by the Fz amplitude and Mini Mental State Examination and apathy scores. Logistic regression analysis showed that Fz amplitude, verbal fluency, and Neuropsychiatric Inventory total scores distinguished AD patients from HCs, while the Stroop 5 completion time distinguished those with MCI from HCs. Age, Fz amplitude, and verbal fluency performance distinguished AD patients from individuals with MCI.

Conclusion: MMN might be a useful approach in differentiating AD from MCI and healthy aging when used together with neuropsychological tests rather than being used alone because it may be affected by confounding factors such as age, severity of temporoparietal neurodegeneration, and duration of the interstimulus interval.