Alterations Of The Dynamic Spontaneous Neural Activities And Integration In Vascular Mild Cognitive Impairment

Objective:Vascular mild cognitive impairment(Va MCI)is an early symptom of cognitive impairment caused by cerebrovascular disease.While the majority of current functional network studies on Va MCI have mainly focused on simple scan-length averages,the neurobiological mechanisms of vascular mild cognitive impairment(Va MCI)still remain unclear.Meanwhile,dynamic features of brain activities on Va MCI have received relatively little attention.Nevertheless,the human brain is a complex dynamic system with non-stationary neural activities and interactions,thus we explored the dynamic changes of neural activities in Va MCI.In this study,we applied a sliding window approach to capture time-varying properties of spontaneous neural activities(including regional homogeneity,amplitude of low-frequency fluctuations and degree centrality)and their integration capability in Va MCI patients.We also investigated the correlation between concordance and neuropsychological tests.Materials and Methods:In this study,a total of 47 right-handed individuals were enrolled in the study,including 22 Va MCI patients and 25 healthy controls(HCs)matched for age and sex.All subjects completed the Montreal Cognitive Assessment test after functional MRI examination.We adopted the sliding time window approach to explore the dynamic changes of these indices(Re Ho,ALFF and DC)in patients with Va MCI.Then we calculated the concordance,which means the consistency among different indices.The concordance represents the integration capability at different functional aspects,which may reveal more information about the pathophysiological mechanisms.Furthermore,we evaluated the correlations between concordance and neuropsychological scales to illustrate the clinical significance of concordance.Result:(1)Demographics and neuropsychological testsThere were no differences in age,gender and years of education between the two groups.Va MCI patients showed lower scores than HCs in regarding the cognitive assessment(Mo CA)(2)Dynamic abnormalities of spontaneous neural activitiesThe obtained results revealed statistically significant changes in Va MCI patients.Specifically,compared with HCs,d Re Ho significantly decreased in the bilateral superior temporal gyrus(STG)/middle temporal gyrus(MTG),right lingual gyrus(LING),left postcentral(Po CG)and left rolandic operculum(ROL)(p<0.01 FDR corrected)of Va MCI patients.Va MCI patients also had decreased d ALFF in bilateral caudate(CAU),right STG,right thalamus(THA),and left LING and right precuneus(PCu)/cuneus(Cu),left Po CG(p<0.01 FDR corrected).In the current study,d DC showed no significant difference between the two groups.And the mean of concordance in Va MCI was significantly lower than in HCs(p<0.01).(3)Correlation between concordance and Mo CA scoresFurthermore,the correlation between concordance and Mo CA scores was computed,revealing a significant positive correlation(r = 0.631,p<0.01)between mean of concordance and Mo CA scores.However,the SD of concordance was not correlated with Mo CA scores.Conclusion:In conclusion,we adopted the sliding time window method and combined different indices to investigate the dynamics of neural activities.These abnormal brain activities may suggest incipient neuronal/synaptic dysfunction.The abnormal fluctuations of these indices revealed functional defects in these brain areas and Va MCI patients were unable to control their cognitive activities steadily and effectively.These results could extend the understanding of the neurobiology of cognitive impairment in Va MCI patients.