The Brain Structure Network Changes Of Alzheimer’s Disease And Subcortical Ischemic Vascular Dementia And Relationship Between The Changes And Cognitive Function

Objectives:To explore the evaluation of white matter structural network analysis in differentiation of Alzheimer’s disease(AD)and subcortical ischemic vascular dementia(SIVD),and evaluate the relationship between parameters of structure network and the score of neuropsychological files..Materials and methods:67 participants(31 AD patients,19 SIVD patients and 19 normal control(NC))were enrolled in this study from August 2018 to June 2020.Each participant performed 3,0 T MR scanning and neuropsychological test.The neuropsychological test included Montreal cognitive Assessment(MoCA),mini mental state examination(MMSE),Auditory verbal learning test(AVLT),Stroop word-color test,Digital span test(DST),Clock drawing test(CDT),Verbal fluency test(VFT),Hamilton depression rating scale(HAMD)and Hamilton anxiety rating scale(HAMA).Stroop Color-Word Test included Stroop test 1 and Stroop test 2.The Stroop test 1 and Stroop test 2 measured the executive function of participants.A three-dimensional fast spoiled gradient recalled(3DFSPGR)sequence,diffusion tensor imaging(DTI),axial T2-weighted sequence,diffusion weighted imaging(DWI)and T2-weighted flair sequence were obtained in our study.DTI data were analyzed by structure network analysis.Statistical analyses of global parameters(Gamma,Sigma,Lambda,global shortest path length(Lp),global efficiency(Eg)and local efficiency(Eloc))and nodal parameters(betweenness centrality(BC))were obtained.Network based statistical analysis(NBS)was employed to analyze the group differences of structural connections.The diagnosis efficiency of nodal BC in identifying different types of dementia was assessed by receiver operating characteristic(ROC)analysis.The relationships between the parameters of structure network and the scores of neuropsychological scales were analyzed by Spearman’s correlation analysis.Results:There were no significant differences of gender and years of education among the groups(P>0.05).Although the scores of MoCA,MMSE,AVLT,CDT,VFT and HAMA in AD and SIVD group were significantly decreased when SIVD patients compared with NC and AD patients compated with NC(P<0.05),there were no significant differences in the result of such neuropsychological sclaes when AD patients compared with SIVD patients(P<0.05).When AD patients compared with SIVD patients and NC compared with SIVD patients,Stroop test 1 and 2 of SIVD patients were significantly reduced(P<0.05).The Sigma values of SIVD patients,AD patients and NC group were more than 1.There were no significant differences of Sigma and Gamma in AD versus NC and SIVD versus NC(P>0.05),whereas the Eg values of AD and SIVD were statistically decreased and Lambda values of them were increased(P<0.05).The Lp of SIVD patients were significantly increased when SIVD patients compared with NC and SIVD patients compared with AD patients(P<0.05).The BC of left inferior frontal gyrus(orbital part),left superior frontal gyrus(medial part),right rolandic operculum,right postcentral,left superior parietal gyrus and left precuneus in AD patients were reduced obviously when AD patients compared with NC(P<0.001).Compared with NC,SIVD patients demonstrated decreased BC mainly involved in prefrontal regions,such as right superior frontal gyrus,right superior frontal gyrus(orbital part),right inferior frontal gyrus(opercular part)and left anterior cingulate gyrus,as well as in right putamen and right superior occipital gurus(P<0.001).SIVD patients were with decreased structural connections in frontal,prefrontal and subcortical regions,while AD patients decreased in temporal and occipital regions and increased in frontal and prefrontal regions(P<0.05).The highest area under curve(AUC)of BC was 0.946 in right putamen when AD versus SIVD.The scores of MMSE and MoCA were correlated with the values of Eg in AD patients(r=0.319,P=0.08;r=0.467,P=0.008).There were no correlations between the value of Eg and the scores of CDT,VFT,AVLT and HAMA in AD patients(P>0.05).The scores of AVLT-IR were correlated with the value of Lp and Eg in SIVD patients(r=-0.489,P=0.033,r=0.489,P=0.033).The scores of Stroop test 2 were positively correlated with the value of Lambda in SIVD patients(r=0.532,P=0.019).The scores of VFT in SIVD patients were positively correlated with the value of Eloc(r=0.544,P=0.016).There were no correlations between the global topological parameters and the scores of MMSE and MoCA in SIVD patients.The BC values of left inferior frontal gyrus(orbital part)were obviously correlated with the scores of AVLT-DR in AD patients(r=-0.376,P=0.037).The BC values of right Putamen were negatively correlated with the results of VFT in SIVD patients(r=-0.578,P=0.010).Conclusions:White matter structural network analysis may be a potential and promising method,and the topological changes of the network,especially the BC change in right putamen,were valuable in differentiating AD and SIVD patients.Executive dysfunction is the hallmark of SIVD patients.