Stevens A, Kircher T
Klinik für Psychiatrie und Psychotherapie, Universität Tübingen, Germany.
Eur Arch Psychiatry Clin Neurosci. 1998;248(5):259-66. doi: 10.1007/s004060050047.
The diagnosis of beginning dementia is based mainly on neuropsychological testing. Several measures of EEG spectral composition, coherence and complexity (correlation dimension) have been shown to correspond to cognitive function. Only a few studies have evaluated EEG changes in normal aging, and no quantitative study has addressed changes in EEG during cognitive tasks in demented elderly. In this study the quantitative descriptors of EEGs from 31 demented or cognitively impaired elderly persons, 30 healthy elderly (mean age 69 years) and 35 young controls (mean age 31 years) were compared. The EEGs were recorded during two resting conditions (eyes closed and eyes opened) and two tasks (mental arithmetics and a lexical decision). The goal of the study was to evaluate which temporal and spatial EEG descriptors change with cognitive decline and with normal aging, respectively. Cognitive categories (unimpaired, impaired, demented) were based on Structured Interview for the Diagnosis of Dementia of Alzheimer Type (SIDAM) scores. The EEGs were analysed using adaptive segmentation of continuous EEG, which quantifies the succession of distinct stable topographic voltage patterns (EEG microstates). The main findings were a significant increase in the number of ultra-short EEG microstates and, independently, a reduction in the average duration of EEG microstates in the cognitively impaired and demented patients. In addition, cognitive impairment was associated with a reduction or loss of EEG reactivity normally observed when the resting states with closed and with opened eyes are compared. No alterations in temporal or spatial EEG descriptors were found in normal aging. Cognitive tasks did not add to information already obtained during the resting states. The reduction in EEG microstate duration correlated with loss of cognitive function. Temporo-spatial analysis of EEG therefore is a useful indicator of cortical dysfunction in dementia, correlating with the degree of cognitive impairment. Normal aging seems not to be accompanied by changes in temporo-spatial EEG patterns. The data suggest that fragmentation of the electrophysiological processes underlies cognitive dysfunction in Alzheimer's disease.
早期痴呆的诊断主要基于神经心理学测试。脑电图频谱组成、相干性和复杂性（关联维数）的多项指标已被证明与认知功能相关。仅有少数研究评估了正常衰老过程中的脑电图变化，尚无定量研究探讨痴呆老年人在认知任务期间的脑电图变化。在本研究中，对31名痴呆或认知受损老年人、30名健康老年人（平均年龄69岁）和35名年轻对照者（平均年龄31岁）的脑电图定量描述符进行了比较。在两种静息状态（闭眼和睁眼）以及两项任务（心算和词汇判定）期间记录脑电图。本研究的目的是分别评估哪些时间和空间脑电图描述符会随着认知衰退和正常衰老而变化。认知类别（未受损、受损、痴呆）基于阿尔茨海默病型痴呆诊断结构化访谈（SIDAM）评分。使用连续脑电图的自适应分割对脑电图进行分析，该方法可量化不同稳定地形电压模式（脑电图微状态）的序列。主要发现是，认知受损和痴呆患者的超短脑电图微状态数量显著增加，且独立地，脑电图微状态的平均持续时间缩短。此外，认知障碍与闭眼和睁眼静息状态比较时通常观察到的脑电图反应性降低或丧失有关。在正常衰老过程中未发现时间或空间脑电图描述符有改变。认知任务并未增加在静息状态期间已获得的信息。脑电图微状态持续时间的缩短与认知功能丧失相关。因此，脑电图的颞 - 空间分析是痴呆中皮质功能障碍的有用指标，与认知障碍程度相关。正常衰老似乎并未伴有颞 - 空间脑电图模式的变化。数据表明，电生理过程的碎片化是阿尔茨海默病认知功能障碍的基础。
