Impaired Long Distance Functional Connectivity and Weighted Network Architecture in Alzheimer's Disease
Impaired Long Distance Functional Connectivity and Weighted Network Architecture in Alzheimer's Disease
复制标题
阿尔茨海默病中的长距离功能连接和加权网络架构受损。
DOI：
10.1093/cercor/bhs410
复制
发表时间：
2014-06-01
期刊：
影响因子：
3.7
通讯作者：
Bullmore, Edward T.
中科院分区：
文献类型：
--
作者：
Liu, Yong;Yu, Chunshui;Bullmore, Edward T.
阿尔茨海默病（AD）日益被视为一种失联综合征，由于相互连接的大脑区域所构成的大型网络或系统的功能活动中断，从而导致认知障碍。我们在一组重度阿尔茨海默病患者（N = 18）和年龄匹配的健康志愿者（N = 21）样本中，探究了功能性磁共振成像（fMRI）静息态动力学、功能连接性以及加权功能网络的异常情况。我们发现，患者低频fMRI振荡的幅度和区域同质性降低，并且在一些先前被描述为默认模式网络组成部分的区域，例如内侧后顶叶皮层和背内侧前额叶皮层，功能连接性强度降低。在重度阿尔茨海默病患者中，物理距离较远的区域之间的功能连接性尤其减弱；长距离连接性的丧失与整体和节点网络拓扑结构效率降低有关。重度阿尔茨海默病的这种功能异常特征与对另外两组轻度阿尔茨海默病患者（N = 17）和遗忘型轻度认知障碍（MCI；N = 18）数据的类似分析结果一致。通过对所有患者组进行简易精神状态检查所测量的认知障碍程度越高，与功能连接性的减弱程度越大相关，特别是在长连接距离上，例如默认模式网络的前部和后部组件之间，以及整体和节点网络效率的降低程度越大相关。这些结果表明，阿尔茨海默病中fMRI振荡和连接性的神经退行性破坏影响到与枢纽节点的长距离连接，从而导致网络效率的丧失。这种特征在认知障碍较轻的患者中也有一定程度的体现，这表明静息态fMRI测量作为阿尔茨海默病疾病进展的生物标志物或预测指标的潜力。
Alzheimer's disease (AD) is increasingly recognized as a disconnection syndrome, which leads to cognitive impairment due to the disruption of functional activity across large networks or systems of interconnected brain regions. We explored abnormal functional magnetic resonance imaging (fMRI) resting-state dynamics, functional connectivity, and weighted functional networks, in a sample of patients with severe AD (N = 18) and age-matched healthy volunteers (N = 21). We found that patients had reduced amplitude and regional homogeneity of low-frequency fMRI oscillations, and reduced the strength of functional connectivity, in several regions previously described as components of the default mode network, for example, medial posterior parietal cortex and dorsal medial prefrontal cortex. In patients with severe AD, functional connectivity was particularly attenuated between regions that were separated by a greater physical distance; and loss of long distance connectivity was associated with less efficient global and nodal network topology. This profile of functional abnormality in severe AD was consistent with the results of a comparable analysis of data on 2 additional groups of patients with mild AD (N = 17) and amnestic mild cognitive impairment (MCI; N = 18). A greater degree of cognitive impairment, measured by the mini-mental state examination across all patient groups, was correlated with greater attenuation of functional connectivity, particularly over long connection distances, for example, between anterior and posterior components of the default mode network, and greater reduction of global and nodal network efficiency. These results indicate that neurodegenerative disruption of fMRI oscillations and connectivity in AD affects long-distance connections to hub nodes, with the consequent loss of network efficiency. This profile was evident also to a lesser degree in the patients with less severe cognitive impairment, indicating that the potential of resting-state fMRI measures as biomarkers or predictors of disease progression in AD.