A Study On Salient Network Characteristic Patterns And Brain Network Topological Properties In Patients With Subjective Cognitive Decline And Amnestic Mild Cognitive Impairment

Part Ⅰ altered patterns of structural and functional within the salience network in subjective cognitive decline and amnesic mild cognitive impairment Objective: The spectrum of preclinical Alzheimer’s disease(AD)was considered to include subjective cognitive decline(SCD)and amnestic mild cognitive impairment(aMCI).Salience network(SN)has attracted wide attention because of its important role in higher cognitive function.Studies have shown that there was a extensive impairment of the SN in AD spectrum.However,it was not clear whether SCD and aMCI shared common and specific changes in the structure and function of SN.The purpose of this study was to explore the potential damage of the structure and function of SN in SCD and aMCI,and to further explore whether the combination of structural and functional changes in SN can effectively diagnose SCD and aMCI.Methods: Structural and resting-state functional magnetic resonance imaging were collected in 44 SCD,49 aMCI and 59 healthy control(HC).Cortex thickness,gray matter(GM)volume,regional homogeneity,fractional amplitude of low frequency fluctuations(f ALFF),functional connectivity(FC)within SN,and its relationship with cognitive function were analyzed.The receiver operating characteristic analysis was performed to assess diagnostic efficacy of single altered indictor and combined indictor for SCD and aMCI.Results: Compared with HC,SCD showed decreased GM volume within SN in the bilateral superior temporal gyrus(STG),bilateral inferior frontal gyrus and left middle frontal gyrus(IFG),decreased f ALFF in the right inferior parietal lobule(IPL)and right superior marginal gyrus(SMG),and increased FC in the right IFG.Compared with HC,aMCI showed decreased cortex thickness in the caudal cortex of the right anterior cingulate gyrus,decreased f ALFF in the right IPL and the right SMG,and increased FC in the right STG and left inferior temporal gyrus.Compared with SCD,aMCI showed increased FC in the right HIP and right STG within SN,and decreased FC in the left middle temporal gyrus(MTG).Moreover,the altered FC in SCD and aMCI in the left MTG,right STG,and right HIP were significantly correlated with cognitive function.Particularly,the classification accuracy of SCD and HC based on the combined multiple indicators was 0.852,aMCI and HC was0.937,and SCD and aMCI was 0.931.Conclusion: Structure and function of SN were disrupted in SCD and aMCI which involved in cognitive decline.The combined multiple indicators of SN provided new and powerful biomarkers for the diagnosis and differentiation of SCD and aMCI.Part Ⅱ Altered topological properties of brain networks in subjective cognitive decline and amnestic mild cognitive impairmentObjective: Subjective cognitive decline(SCD)and amnestic mild cognitive impairment(aMCI)were considered to be the spectrum of preclinical Alzheimer’s Disease(AD).Rich-club organization was composed of brain regions with high nodal degree,which was widely believed to reveal the pathology of AD spectrum.However,there are few studies on the disrupted pattern of diverse-club organization and the combination of the rich-club and diverse-club organizations in SCD and aMCI.The purpose of the study was to explore the change of rich-club and diverse-club organizations in SCD and aMCI,as well as the influence of node attribute values change on cognitive function.Methods: Resting state f MRI data were collected from 19 SCD,29 aMCI,and 28 healthy control(HC).Graph theory analysis was used to analyze the rich-club and diverse-club organizations simultaneously.Based on the graph theory analysis method,the rich-club and divers-club organization were divided by the nodal degree and nodal participation coefficient.Subsequently,analysis of variance and post-hoc analysis was used to calculate changes in the three-class connections of the three groups,as well as the node attributes of the overlapping nodes of the rich-and diverse-club.In addition,Pearson correlation analysis was used to investigate the relationship between altered node attribute values and neurocognitive performance.Results: Compared with HC,the aMCI group showed reduced rich-club connectivity.In addition,the aMCI group showed significantly increased feeder connectivity and decreased local connectivity of the diverse-club compared with the SCD group.The overlapping nodes of the rich-club and diverse-club showed a significant difference in nodal efficiency and shortest path length(Lp)between groups.Notably,the Lp values of overlapping nodes in the SCD and aMCI groups were significantly associated with episodic memory.Conclusion: The combination of the rich-club and the diverse-club can provide a novel insight into the pathological mechanism of the AD spectrum.The altered patterns in overlapping nodes might be potential biomarkers in the diagnosis of the AD spectrum.