不同认知功能域受损的轻度认知障碍患者脑功能网络拓扑属性的研究

Study on the topological properties of brain functional networks in patients with mild cognitive impairment with different cognitive domains

目的:探讨不同认知功能域受损的轻度认知障碍(mild cognitive impairment,MCI)患者脑功能网络拓扑属性的变化。方法:收集简易智能精神状态检查量表>24分,蒙特利尔认知评估量表≤25分,临床痴呆量表为0.5分的MCI患者31例,根据认知功能域评定量表分为存在记忆力差别、执行力差别、注意力差别、语言能力差别和视空间能力差别的5组实验组和相匹配的对照组,对每组患者进行脑功能网络的构建和网络拓扑属性的分析。结果:以连接矩阵的稀疏度(sparsity)为阈值,在0.09~0.16范围内,所有MCI患者的脑功能网络拓扑参数σ均>1,均具有小世界属性。其中,记忆力更好的实验组1患者的σ和γ等脑功能网络小世界参数均明显高于对照组1患者,差异有统计学意义(P<0.05),视空间能力更好的实验组5患者的λ、Eloc和Eglob等脑功能网络小世界参数均明显高于对照组5患者,LP小世界参数明显低于对照组5患者,差异有统计学意义(P<0.05),其余认知功能域不同的MCI患者在脑功能网络小世界参数的组间对比差异均无统计学意义(P>0.05)。结论:MCI患者的脑功能网络均表现出小世界属性,其中记忆力和视空间能力更差的MCI患者出现网络拓扑结构的破坏,可能与AD患者早期出现情景记忆受损及空间认知障碍等症状相关,这为预测MCI患者进展为AD的可能性提供了新的神经生理学机制的参考,同时指导临床医师在针对MCI患者的认知干预方面应加强对记忆力和视空间能力的训练,可以最大程度地改善患者脑功能网络拓扑结构的破坏。

Objective:To investigate the changes of topological properties of brain functional networks in patients with mild cognitive impairment with different cognitive functional domains.Methods:To collect 31 MCI patients with a summary of MMSE>24 points,MoCA≤25 points and a clinical dementia scale of 0.5.According to the cognitive function domain evaluation scale,five groups of experimental group and matched control group were divided into memory difference,executive ability difference,attention difference,language ability difference and visual space ability difference.The brain function network construction and network topology attribute were analyzed in each group.Results:A threshold of sparsity of the connection matrix,the topological parametersσof brain functional network in all MCI patients>1,all have small world attributes.The small world parameters of brain function network such asσandγin experimental group1 with better memory were significantly higher than those in control group1(p<0.05).Theλ、Eloc and Eglob small world parameters of brain function network in the experimental group5 were significantly higher than those in the control group5,and the LP small world parameters were significantly lower than those in the control group5(p<0.05).There was no significant difference between the other MCI patients with different cognitive domains in the small world parameters of brain functional network(p>0.05).Conclusions:Brain functional networks of MCI patients show small world attributes,in which memory and visual space ability are worse MCI patients have network topology destruction,which may be related to the early occurrence of situational memory impairment and spatial cognitive impairment in AD patients.This provides a new neurophysiological mechanism for predicting the possibility of AD and instructs clinicians to strengthen the training of memory and visual space ability in cognitive intervention for MCI patients,which can improve the destruction of brain functional network topology to the greatest extent.