The Correlation Of Cognitive Decline And DTI Network Properties In Patients With White Matter Lesions

ObjectiveWhite matter lesions(WML),also identified as white matter hyperintensities(WMH)are localized areas of increased signal in the brain white matter visible on T2-weighted images.Along with the development of medical imaging technology,such as brain magnetic resonance imaging including white matter hyperintensities volume measurement and white matter network reconstruction,providing a new perspective for the study of white matter lesions.However,the correlation of cognitive decline and white matter lesions still remained unclear.We found that patients with cerebral white matter lesions did not necessarily vulnerable to cognitive dysfunction which suggest the contribution of other pathological elements.Therefore in this study,by automatic quantitative measurement of the volume of white matter lesions,we attempt to determinethe correlation between cognitive dysfunction and the location and volume of white matter lesions.Furthermore,by reconstruction of the brain DTI network we compared the global and local network changes between white matter lesions patients with or without cognitive impairment to determine the brain regions that are associated with cognitive dysfunction.MethodsParticipants:sixty-three patients with white matter lesions detected by magnetic resonance were included in the study.A Set of neuropsychological scales which include the Mini-mental state examination(MMSE),Montreal cognitive assessment(MoCA),the clinical dementia rating scale(CDR),clock drawing test(CDT)and verbal fluency test fluency test(VFT)were applied for neuropsyehological assessments.According to the score of cognitive scales,all the participants were divided into cognitive normal group(CN),mild cognitive impairment(MCI)and mixed dementia group(MD).2.1 Neuropsyehological assessment:A Set of neuropsychological assessment scale include:MMSE(MMSE),Montreal cognitive assessment(MoCA),the clinical dementia rating scale(CDR)assessment of cognitive function in general;clock drawing test(CDT)evaluation patients with executive function;verbal fluency test fluency test(VFT)(animal)assessment of the patient’s language function.2.2 Images were acquired on a 3.0 tesla MR scanner(Achieva TX,Philips).Each subject underwent the T1 weighted imaging(T1WI),T2 weighted imaging(T2WI),diffusion weighted imaging(DWI),fluid attenuated inversion recovery imaging(FLAIR)and diffusiontensor imaging(DTI).Automatic white matter hyperintensities volume measurement was applied for white matter lesions evaluation and DTI network construction was performed by PANDA for graph theory analysis.Statistical analysis was performed by the SPSS 19.0.ResultsPVL volume of the CN,MCI and MD subjects were 2916.85±6094.44mm~3,4906.82±6922.15 mm~3,15417.99±26675.96 mm~3.Significant differences of PVL volume was observed between the groups(P<0.05),while no significant differences ofDWMLvolumewerefound(CN,970.22±2817.92mm~3;MCI,1537.38±3062.75mm~3;MD,6614.78±15312.01mm~3;P=0.36).No significant differences of total white matter hyperintensities volume(CN,1946.63±3330.22 mm~3;MCI,3369.44±3964.74 mm~3;MD,8803.21±11640.16 mm~3)were found among the groups neither(P=0.08).A negative correlation between the overall cognitive dysfunction and white matter lesions volume was observed by the Spearman correlation analysis(P<0.05).Multivariate linear regression analysis indicated a significant correlation between cognitive decline and PVL volume in all three cohorts(P<0.05).Global efficiency of DTI network were 0.18±0.02(NC),0.17±0.02(MCI)and 0.15±0.02(MD)and significant differences were observed among the groups(P<0.05).Significant differences of the shortest path among the groups(CN,5.61±0.51;MCI,5.94±0.66;MD,6.76±0.80)were observed(P<0.05)and higher path length of the MD subjects were detected by the LSD test(P<0.05).No differences of the clustering coefficient(CN,0.43±0.02;MCI,0.42±0.04;MD,0.41±0.05)were observed among the groups(P=0.08).A positive correlation between MoCA and the network node efficiency of the right orbital inferior frontal gyrus,right posterior cingulate,right hippocampus,left occipital gyrus,right occipital gyrus,right precuneus,left putamen,right lentiform pallidum,right temporal pole,superior temporal gyrus,right temporal pole,middle temporal gyrus and right inferior temporal gyrus were detected(P<0.05).There was a significant positive correlation between MoCA and network node degree in the left occipital gyrus,right occipital gyrus,right precuneus,left putamen and right putamen in all three cohorts(P<0.05).Significant correlation between MoCA and network node betweenness were observed in the left middle frontal gyrus,right central sulcus,cover the top edge of right angular gyrus,right supramarginal gyrus and right angular gyrus(P<0.05).ConclusionIn this study,we detected a correlation between the volume of white matter lesions and cognitive decline.Volume of white matter hyperintensities is correlated with cognitive decline and especially with executive dysfunction.The graph theory analysis indicated that the global efficiency of MD patients was significantly lower than that of MCI and CN subjects,while the shortest path length of MD patients was higher than that of MCI and CN subjects.Abnormalities of local network properties in the hippocampus,temporal lobe and other cognition related brain regions are associated with cognitive impairment in patients with white matter lesions,which indicated that the white matter lesions might compromised the brain network integrity and resulted in cognitive dysfunction.