健康与遗传心理学研究室知识库

我国己经步入老龄化社会。伴随人口老化而来的脑老化神经退行性疾病，阿尔茨海默病成为影响国民生活质量、阻碍社会发展的一大公共健康问题。阿尔茨海默病起病隐匿，其发展是一个长期的过程，以现今的医疗水平，还没有能够有效地治疗阿尔茨海默病的方法。但是如果可以尽早发现潜在的患者，并及时地进行干预，将有效地延缓疾病发展的速度。随着非侵入式影像技术的发展，基于磁共振成像的阿尔茨海默病研究表明阿尔茨海默病患者的大脑结构以及功能都发生了改变。其中，功能磁共振研究表明阿尔茨海默病是一种“打乱原有连接模式”的疾病，阿尔茨海默病患者的脑功能连接网络经历了变化。人脑功能连接无疑是具有时空多尺度特性的，但是目前研究只是从单一尺度对这种脑功能网络的变化进行研究。随着阿尔茨海默病疾病发展，脑功能网络的变化在各个尺度上如何变化，阿尔茨海默病不同阶段是否更倾向于特定尺度的变化，以及这些变化是否与行为分数相关，都是需要进行研究的问题。本研究拟采用多尺度的中心度指标研究阿尔茨海默病病程中大脑功能连接模式的变化。其中，局部尺度的中心度指标为度中心度;中间尺度的中心度指标为子图中心度;全局尺度的中心度指标为特征向量中心度和网页排序中心度。本研究将计算主观认知下降患者、遗忘型轻度认知功能损害患者、阿尔茨海默病患者的各个中心度图谱，比较他们和正常老年人中心度图谱在多个尺度上的差异，并探究这种功能网络变化和行为分数的关系。结果表明，主观认知下降患者在视觉和感觉运动区域表现出中间尺度的中心度降低;遗忘型轻度认知功能损害患者表现出默认，边缘和背侧注意网络多个尺度中心度的下降，额顶控制网络局部尺度中心度的下降，和感觉运动网络全局尺度中心度的上升和下降;阿尔茨海默病患者表现出全局尺度的中心度上升，包括初级和联合皮层等。由此我们推断，阿尔茨海默病的脑功能连接变化随着疾病发展，从由中间尺度发展为多个尺度再到全局尺度，且从初级的感觉运动等区域发展到默认、注意网络等联合皮层。中心度作为一种基于体素水平描述脑网络属性的方法，为我们理解阿尔茨海默病病理机制及观察其大脑功能连接模式的改变提供了一个新视角。

China has already stepped into an aging society. Alzheimer's disease, thus, has become a problem we have to face. Alzheimer's disease (AD) is a chronic neurodegenerative disease, and no treatments stop or reverse its progression. However, early detection, facilitates the prevention that might slow the progression of Alzheimer's disease. With the aid of non-invasive neuroimaging technologies, researchers have found both structural and functional alterations of patients with Alzheimer's disease. Thereinto, Alzheimer's disease is described as a disease with disrupted connectivity. Clearly, the brain is a dynamic complex network that spans not only temporal scales but also spatial scales. Existing research merely examined brain connectivity patterns at a single scale. It remains unknown how brain connectivity changes at different scales during the progression of Alzheimer's disease, whether different stage of Alzheimer's disease is related to a particular scale and whether alterations at certain scales can predict cognitive performance. To this end, we applied centrality measures at multi-scale, to be specific, degree centrality (local scale), subgraph centrality (meso-scale), eigenvector centrality and page-rank centrality (global scale), to the investigation of the entire Alzheimer's disease. Our results revealed that compared to normal aging, patients with subjective cognitive decline showed meso-scale declines in the primary areas; patients with amnestic mild cognitive impairment demonstrated diminished centralities at multi-scale in the associative areas and bi-directional changes in the primary areas; and subjects with Alzheimer's disease manifested global abnormalities in large-scale brain network. Our findings indicated a multi-scale connectivity profile for Alzheimer's disease that involves the meso-multiple-global scales and primary-associative networks of alterations. Centrality, as a voxel-vise measure of brain network properties, provides us with insights into the elucidation of Alzheimer's disease pathology.