Changes Of Small-world Properties Of Functional Brain Networks And Correlation With Cognition In Alzheimer’s Disease

Objective:To investigate the changes of small-world properties of functional brain networks and their correlations with cognition in Alzheimer’s disease(AD)patients using graph theory analysis method.Methods:Neuropsychological assessment and resting-state f MRI data were acquired on42 AD patients(AD group)and 31 normal volunteers(control group).Firstly the small-world network was constructed,and then the small-world properties,including the clustering coefficients(Cp),shortest path length(Lp),normalized clustering coefficients(γ),normalized shortest path length(λ)and small-worldness(σ)were calculated.The changes of relevant parameters between AD group and control group were examined using two-sample t tests,and partial correlation analyses were used to evaluate the correlation between small-world network properties and cognition.Results:Under the range of different sparsities,the σ>1 was found in both groups,indicating that the property of the functional networks in AD and control groups fit the definition of small-worldness.The Lp and λ of the small-world network in the AD group were significantly greater than those in the control group(both P<0.05),while there were no significant differences of Cp,γand σ between the 2 groups(all P>0.05).The Cp of AD group was positively correlated with the performance of auditory verbal learning test(AVLT,immediate)scores and AVLT(delay)scores(r=0.646,0.438,P<0.001,P=0.008).The Lp in AD group was negatively correlated with AVLT(immediate,r=-0.381,P=0.035).Conclusions:The small-world properties of functional brain networks in AD patients have been changed and significantly correlated with the performance of episodic memory.The changes of small-world network properties of functional brain network may reflect the pathophysiological changes of AD patients.