Niu Haijing, Zhu Zhaojun, Wang Mengjing, Li Xuanyu, Yuan Zhen, Sun Yu, Han Ying
Beijing Normal University, State Key Laboratory of Cognitive Neuroscience and Learning and IDG/McGovern Institute for Brain Research, Beijing, China.
Xuan Wu Hospital of Capital Medical University, Department of Neurology, Beijing, China.
Neurophotonics. 2019 Apr;6(2):025010. doi: 10.1117/1.NPh.6.2.025010. Epub 2019 Jun 4.
Communication within the brain is highly dynamic. Alzheimer's disease (AD) exhibits dynamic progression corresponding to a decline in memory and cognition. However, little is known of whether brain dynamics are disrupted in AD and its prodromal stage, mild cognitive impairment (MCI). For our study, we acquired high sampling rate functional near-infrared spectroscopy imaging data at rest from the entire cortex of 23 patients with AD dementia, 25 patients with amnestic mild cognitive impairment (aMCI), and 30 age-matched healthy controls (HCs). Sliding-window correlation and k-means clustering analyses were used to construct dynamic functional connectivity (FC) maps for each participant. We discovered that the brain's dynamic FC variability strength ( ) significantly increased in both aMCI and AD group as compared to HCs. Using the value as a measurement, the classification performance exhibited a good power in differentiating aMCI [area under the curve ( )] or AD ( ) from HCs. Furthermore, we identified two abnormal brain FC states in the AD group, of which the occurrence frequency ( ) exhibited a significant decrease for the first-level FC state (state 1) and a significant increase for the second-level FC state (state 2). We also found that the abnormal in these two states significantly correlated with the cognitive impairment in patients. These findings provide the first evidence to demonstrate the disruptions of dynamic brain connectivity in aMCI and AD and extend the traditional static (i.e., time-averaged) FC findings in the disease (i.e., disconnection syndrome) and thus provide insights into understanding the pathophysiological mechanisms occurring in aMCI and AD.
大脑内部的交流具有高度动态性。阿尔茨海默病（AD）呈现出与记忆和认知能力下降相对应的动态进展。然而，对于AD及其前驱阶段——轻度认知障碍（MCI）中大脑动力学是否受到破坏，人们知之甚少。在我们的研究中，我们采集了23例AD痴呆患者、25例遗忘型轻度认知障碍（aMCI）患者以及30名年龄匹配的健康对照（HCs）静息状态下整个皮层的高采样率功能近红外光谱成像数据。使用滑动窗口相关性和k均值聚类分析为每个参与者构建动态功能连接（FC）图。我们发现，与HCs相比，aMCI组和AD组大脑的动态FC变异性强度（ ）均显著增加。以 值作为测量指标，分类性能在区分aMCI [曲线下面积（ ）] 或AD（ ）与HCs时表现出良好的效能。此外，我们在AD组中识别出两种异常的大脑FC状态，其中一级FC状态（状态1）的出现频率（ ）显著降低，二级FC状态（状态2）的出现频率显著增加。我们还发现这两种状态下的异常 与患者的认知障碍显著相关。这些发现首次证明了aMCI和AD中动态大脑连接的破坏，并扩展了该疾病中传统的静态（即时间平均）FC研究结果（即失连接综合征），从而为理解aMCI和AD中发生的病理生理机制提供见解。
