Yıldırım Elif, Soncu Büyükişcan Ezgi
Turk Psikiyatri Derg. 2019 Winter;30(4):279-286.
Alzheimer's Disease (AD) is a neurodegenerative condition characterized by functional and structural changes in the brain that are increasingly better visualized with the advances in new brain imaging techniques. Connectivity changes under the resting state condition especially in the internal connectivity network, named as the default mode network (DMN), are observed in AD. This paper aimed to investigate and discuss the findings on DMN connectivity.
The studies carried out by functional magnetic resonance imaging (fMRI), using the two most widely applied techniques, the seed-based method and independent component analysis (ICA), have been investigated.
Studies generally indicate a progressive impairment in DMN connectivity during the course of AD. It has been also stated that DMN subsystems show differential connectivity patterns in the preclinical and prodromal stages of AD. There is also evidence suggesting that impairment in DMN connectivity could be associated with different connectivity patterns in other networks. Furthermore, findings point towards a relationship between DMN and AD-related neuropathology and genetic risk factors.
It may be proposed that AD is a generalized disconnection syndrome that causes functional impairments in resting state networks, particularly in DMN. In addition to this, AD-related functional connectivity changes observed in preclinical cases and risk carriers might be a potential bio-marker for AD.
阿尔茨海默病（AD）是一种神经退行性疾病，其特征是大脑发生功能和结构变化，随着新的脑成像技术的进步，这些变化越来越容易被观察到。在AD中观察到静息状态下的连接性变化，尤其是在被称为默认模式网络（DMN）的内部连接网络中。本文旨在研究和讨论关于DMN连接性的研究结果。
对使用功能磁共振成像（fMRI）、采用两种应用最广泛的技术（基于种子点的方法和独立成分分析（ICA））所开展的研究进行了调查。
研究普遍表明，在AD病程中DMN连接性会逐渐受损。也有人指出，DMN子系统在AD的临床前期和前驱期表现出不同的连接模式。还有证据表明，DMN连接性受损可能与其他网络中不同的连接模式有关。此外，研究结果表明DMN与AD相关神经病理学和遗传风险因素之间存在关联。
可以提出，AD是一种全身性的连接障碍综合征，会导致静息状态网络，尤其是DMN出现功能损害。除此之外，在临床前期病例和风险携带者中观察到的与AD相关的功能连接性变化可能是AD的一种潜在生物标志物。
