IRCCS San Camillo Hospital, Venice, Italy.
Division of Brain, Imaging and Behaviour-Systems Neuroscience, Krembil Research Institute, UHN, University of Toronto, Toronto, ON, Canada.
Brain. 2019 Sep 1;142(9):2860-2872. doi: 10.1093/brain/awz192.
Dynamic functional connectivity captures temporal variations of functional connectivity during MRI acquisition and it may be a suitable method to detect cognitive changes in Parkinson's disease. In this study, we evaluated 118 patients with Parkinson's disease matched for age, sex and education with 35 healthy control subjects. Patients with Parkinson's disease were classified with normal cognition (n = 52), mild cognitive impairment (n = 46), and dementia (n = 20) based on an extensive neuropsychological evaluation. Resting state functional MRI and a sliding-window approach were used to study the dynamic functional connectivity. Dynamic analysis suggested two distinct connectivity 'States' across the entire group: a more frequent, segregated brain state characterized by the predominance of within-network connections, State I, and a less frequent, integrated state with strongly connected functional internetwork components, State II. In Parkinson's disease, State I occurred 13.89% more often than in healthy control subjects, paralleled by a proportional reduction of State II. Parkinson's disease subgroups analyses showed the segregated state occurred more frequently in Parkinson's disease dementia than in mild cognitive impairment and normal cognition groups. Further, patients with Parkinson's disease dementia dwelled significantly longer in the segregated State I, and showed a significant lower number of transitions to the strongly interconnected State II compared to the other subgroups. Our study indicates that dementia in Parkinson's disease is characterized by altered temporal properties in dynamic connectivity. In addition, our results show that increased dwell time in the segregated state and reduced number of transitions between states are associated with presence of dementia in Parkinson's disease. Further studies on dynamic functional connectivity changes could help to better understand the progressive dysfunction of networks between Parkinson's disease cognitive states.
动态功能连接捕捉到 MRI 采集过程中功能连接的时间变化，可能是检测帕金森病认知变化的一种合适方法。在这项研究中，我们评估了 118 名年龄、性别和教育程度与 35 名健康对照匹配的帕金森病患者。根据广泛的神经心理学评估，将帕金森病患者分为正常认知（n = 52）、轻度认知障碍（n = 46）和痴呆（n = 20）。使用静息状态功能磁共振成像和滑动窗口方法研究动态功能连接。动态分析表明，整个组中存在两种不同的连接“状态”：一种更频繁、更分离的大脑状态，以网络内连接为主，称为状态 I；另一种不太频繁、具有强连接功能网络组件的整合状态，称为状态 II。在帕金森病中，状态 I 出现的频率比健康对照组高 13.89%，状态 II 的比例相应减少。帕金森病亚组分析表明，在帕金森病痴呆中，分离状态比轻度认知障碍和正常认知组更频繁出现。此外，帕金森病痴呆患者在分离的状态 I 中停留的时间明显更长，与其他亚组相比，向强连接的状态 II 的转变次数明显减少。我们的研究表明，帕金森病痴呆的特征是动态连接中时间特性的改变。此外，我们的结果表明，在分离状态下停留时间增加和状态之间转变次数减少与帕金森病痴呆的存在相关。进一步研究动态功能连接变化可以帮助更好地理解帕金森病认知状态之间网络的进行性功能障碍。
