EEG Coherence in Controls, Mild Cognitive Impairment and Different Stage of Alzheimer's Disease

J Korean Neurol Assoc > Volume 24(1); 2006 > Article

Journal of the Korean Neurological Association 2006;24(1): 38-46.

정상노인, 경도인지장애와 알쯔하이머병의 단계에 따른 뇌파 Coherence

효자병원 신경과

EEG Coherence in Controls, Mild Cognitive Impairment and Different Stage of Alzheimer's Disease

Yong Tae Kwak

Department of Neurology, Hyoja Geriatric Hospital, Yongin, Korea

Abstract

Background: EEG coherence can be used to evaluate the functional electrical connections between different cortical regions. We compare EEG coherences among younger controls (YC), elderly controls (EC), mild cognitive impairment (MCI), and different stages of Alzheimer's disease (AD) in order to clarify the electrophysiological changes of aging and process of dementia.
Methods: The EEGs were recorded in 29 YC, 37 EC, 22 MCI, 11 CDR 0.5, 42 CDR1, 51 CDR2, 53 CDR3 AD patients from 19 electrodes with linked-ears reference. Anterior and posterior intrahemispheric, far interhemispheric, and interhemispheric coherence were calculated in study subjects.
Results: Elderly controls showed increased anterior local coherence and decreased posterior local coherence compared to the other groups. This results in diminished posterior-anterior differences compared to that of young controls. Compared to elderly controls, significantly higher far coherence values was noted in the theta, alpha, beta band of MCI, theta, beta band of CDR0.5, beta band of CDR1, CDR2, CDR3. In MCI, the delta band of anterior local coherence was significantly decreased compared to mild to moderate AD, and theta, alpha band of posterior local coherence was significantly increased compared to CDR3 of AD.
Conclusions: The coherence changes of controls, MCI and AD is not simple and not specific enough to differentiate the MCI and early AD from the other groups. These complex patterns may reflect the pathophysiological findings of cholinergic change of AD, and we need to increase the understanding of the electrophysiological relationships among aging, MCI and various stages of AD