Changes Of Topological Properties Of Brain Structural Network In Patients With IRBD And Its Correlation With Cognitive Impairment

Background:Rapid eye movement sleep behavior disorder(RBD)is a common type of parasomnia in clinical practice.The main symptoms are a series of dream deductive behaviors such as somnolence,muscle twitching,boxing and kicking,sitting up from bed,tumbling jumping and even ambulation during rapid eye movement sleep(REM),and the reason is the disappearance of the sluggish state of skeletal muscle during REM in patients.RBD includes idiopathic REM behavior disorder(iRBD)and secondary REM behavior disorder(s RBD).IRBD is closely linked to α-synucleinopathy,patients with iRBD may have mild cognitive impairment and the probability of conversion to α-synucleinopathy as the disease progresses.If timely and effective intervention can be implemented for iRBD,the time to progression to α-synucleinopathy can be delayed.Therefore,exploring the early pathological changes of iRBD and improving the accuracy of its early diagnosis for intervention has become a current research hotspot.According to graph theory principles,the human brain can be likened to a complex network with small-world properties.Diffusion tensor imaging(DTI)can be used to delineate the Trajectory of white matter fiber tracts,according to graph theory principles,the Fractional anisotropic(FA)of DTI is used to construct brain structural network connectivity,which can reflect brain changes.Therefore,we investigated changes in cognitive and brain structural network topological properties in patients with iRBD.Objective:To identify the cognitive changes in patients with iRBD,explore the changes of topological attributes of brain structural networks in the early stage of iRBD,and try to analyze the relationship between cognitive impairment and the changes of topological attributes of brain structural networks in patients with iRBD.Methods:A total of 20 patients with iRBD who visited Henan Provincial People’s Hospital from 2019 to2020 and 22 normal controls matched for age,gender and education level were collected during the same period for evaluation of each cognitive domain scale.Then DTI sequences and T1-three-dimensional fast perturbation gradient echo sequences of the subject’s head were obtained using magnetic resonance scanning.Magnetic resonance data were processed and structural brain networks were constructed using software.Finally,SPSS 22.0 was used for data analysis,and the network data visualization images were generated using Brain Net Viewer software.Results:IRBD had lower scores in ROCFT-copy(P= 0.038),AVLT N1(P= 0.011),AVLT N2(P = 0.002),AVLT N3(P = 0.036),AVLT N4(P = 0.047),and SDMT(P < 0.001)than HC group;The scores of TMT-A(P = 0.019)and TMT-B(P= 0.003)were higher in the iRBD group than in the HC group.The iRBD and HC groups have small-world pattern;There were no statistically significant differences(P > 0.05)in the cluster coefficient(Cp),characteristic path length(Lp),global efficiency(Eglob),and local efficiency(Eloc)of iRBD and HC group;The assortativity of the iRBD group was significantly higher than HC group(P = 0.0233);when the sparsity threshold(S)was less than 0.25,the area under the hierarchy curve(AUC)of the iRBD group was not statistically(P> 0.05)different,but when the sparsity threshold was between 0.25 and 0.5,the area under the hierarchy curve was smaller in the iRBD group than in the HC group(P< 0.05);The left globus pallidus node degree was significantly higher in the iRBD group than in the HC group(P = 0.0005).In the iRBD group,there was a positive correlation between left globus pallidus node degree and AVLT N3(r= 0.368,P=0.161);network assortativity and AVLT N2(r=0.331,P=0.210),network assortativity and AVLT N3(r= 0.395,P= 0.130);area under the network hierarchy curve and AVLT N4(r= 0.358,P =0.173),area under the network hierarchy curve and SDMT(r= 0.424,P= 0.102)scores,but it was not statistically significant.There was a negative correlation between the area under the network hierarchy curve and the TMT-A(r=-0.314,P= 0.236)score,but it was not statistically significant.Conclusion:Patients with iRBD experience early impairment of visuospatial,attention,executive function and memory.In patients with iRBD,the brain structural network is still in a small-world pattern,but changes of increased network assortativity and decreased hierarchy have occurred;changes of increased left globus pallidus node degree have occurred in local topological attributes.There is a trend between altered topological properties of brain structural networks and cognitive impairment(memory,executive function,attention)in patients with iRBD.Altered topological properties of brain structural networks may have affected cognitive function in patients with iRBD.