Global dynamical analysis of the EEG in Alzheimer's disease: Frequency-specific changes of functional interactions
Global dynamical analysis of the EEG in Alzheimer's disease: Frequency-specific changes of functional interactions
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DOI：
10.1016/j.clinph.2007.12.002
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发表时间：
2008-04-01
影响因子：
4.7
通讯作者：
Stam, C. J.
中科院分区：
文献类型：
--
作者：
Jelles, B.;Scheltens, Ph.;Stam, C. J.
目的：阿尔茨海默病（AD）的脑电图连贯性下降，表明脑区之间的相互作用减少。AD的非线性脑电图分析指出，大脑动力学的复杂性降低，意味着相互作用增加。为了从线性和非线性分析中澄清这些明显矛盾的发现，我们计算了可能AD患者和对照组脑电图的全局相干性和全局相关维数（132），这是一种非线性测量。我们的假设是，当以可比的方式计算时，这些措施是相互关联的。方法：选取15例疑似AD患者（平均年龄63.1岁，SD 6.3）和21例年龄匹配且有主观记忆障碍的对照（平均年龄62.8岁，SD 12.0），对6个频段的带滤波脑电图数据进行分析。对于每个频带，确定平均相干性和多通道D-2。结果：重复测量的方差分析显示，D-2在波段和组之间存在相互作用，但没有一致性。在β频带和α频带上，可能AD患者的D-2比对照组高，而可能AD患者在这些频带的整体一致性往往较低。在θ - β频率范围内，相干性与D-2呈负相关，无组间差异。结论：当以可比的方式计算时，全局相关维度和相干性是相关的度量。在阿尔茨海默病中，这些指标在较高的频率范围内发生变化，两者都指向功能性皮质连通性下降。意义：全局相干度和全局相关度似乎都能衡量全球连通性，但非线性度量可能更敏感。在AD中，连通性措施在所有频率范围内受到的损害并不相同，这可能反映了负责不同频段的动态过程的不同影响。(c) 2007年国际临床神经生理学联合会。爱思唯尔爱尔兰有限公司出版。版权所有。
Objective: EEG coherence is decreased in Alzheimer's disease (AD), suggesting decreased interaction between brain areas. Nonlinear EEG analysis in AD points to decreased complexity of brain dynamics, implicating increased interaction. To clarify these apparently paradoxical findings from linear and nonlinear analysis, we calculated global coherence and global correlation dimension (132), a nonlinear measure, in the EEG of patients with probable AD and controls. Our hypothesis is that these measures are related to each other when calculated in a comparable way.Methods: From 15 patients with probable AD (mean age 63.1 years; SD 6.3) and 21 age-matched controls with subjective memory complaints (mean age 62.8; SD 12.0), band filtered EEG data were analysed in six frequency bands. For each frequency band average coherence and multichannel D-2 were determined.Results: ANOVA for repeated measures showed for D-2 an interaction between band and group, but not for coherence. In the beta band and upper alpha band, D-2 was higher in patients with probable AD compared to controls, while global coherence tended to be lower in these frequency bands in patients with probable AD. In the frequency range from theta to beta, coherence and D-2 were inversely correlated without group differences.Conclusions: When calculated in comparable ways, global correlation dimension and coherence are related measures. In AD, these measures change especially in the higher frequency ranges, both pointing to decreased functional cortical connectivity.Significance: Both global coherence and global correlation dimension seem to measure global connectivity, but nonlinear measures may be more sensitive. In AD, connectivity measures are not equally impaired in all frequency ranges, possibly reflecting differentiated affection of the dynamical processes responsible for the different frequency bands. (c) 2007 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.