Study On Changes Of Brain Structure And Brain Network In The Progress Of Alzheimer's Disease With VBM And Rs-fMRI

Objective: To investigate the changes of brain gray matter volume and default mode network in different stages of the course of Alzheimer's disease(AD)from the perspective of morphology and function with voxel-based morphometry(VBM)and resting-state functional magnetic resonance imaging(rs-f MRI).Exploring the pathophysiological mechanism of AD can provide imaging basis for the predictive diagnosis,classification of AD course,and early diagnosis of AD.Materials and Methods: From January 2018 to December 2019,22 patients with Alzheimer's disease(AD),22 patients with mild cognitive impairment(MCI),and 25 patients with subjective cognitive decline(SCD)who were diagnosed by the Department of Neurology and Psychology of the Guizhou Provincial People's Hospital were collected.AD patients were enrolled with the diagnostic criteria issued by the American Institute for Aging and Alzheimer's Disease Association(NIA-AA).MCI patients were enrolled according to the Petersen diagnostic criteria and failed to meet the diagnostic criteria for AD.SCD patients were enrolled with reference to the expert consensus on the diagnosis process and standardization of subjective cognitive decline in Alzheimer's disease in China.During the same period,25 normal volunteers matching the age and sex of the study group were included as the normal control(NC)group.The total sample size was 94 cases,including 40 males and 54 females,with an average age of(70.7 ± 7.22)years.All subjects were scanned with conventional GE 3.0T MR sequences,3D-T1 WI sequences,and rs-f MRI sequences.The structure image uses the VBM method to study the differences in brain gray matter volume in NC,SCD,MCI,and AD.The rs-f MRI images use the posterior cingulated cortex as the seed and getting the default mode network.Then the differences of the default mode network in NC,SCD,MCI,and AD were analyzed.Results: In the comparison of gray matter volume,the brain area of atrophy of the gray matter volume in the AD group compared with the NC group has the left triangular frontal gyrus,the left frontal gyrus,the left central anterior gyrus,the right upper cerebellum,the right orbital frontal gyrus,right middle frontal gyrus,right dorsolateral superior frontal gyrus,left fusiform gyrus.Compared with the SCD group,the brain area of the atrophied gray matter volume in the AD group includes the left middle temporal gyrus,the left wedge lobe,the left central anterior gyrus,the right middle temporal gyrus,and the right lateral cingulate lateral gyrus.Compared with the MCI group,the brain area of matter volume atrophy in the AD group includes the left upper cerebellum,the left medial side,the lateral gyrus,and the right supplementary exercise area.Compared with NC group,the brain area of gray matter volume atrophy in the MCI groups includes the left frontal gyrus,the left dorsolateral frontal gyrus,the left insular lid frontal gyrus,the left supplementary motor area,and the right dorsolateral frontal gyrus.Compared with the SCD group,the atrophy of the gray matter volume in the MCI group includes the left middle temporal gyrus,the left triangular frontal gyrus,and the left corner gyrus.Compared with the NC group,the SCD group had atrophy of the gray matter volume in the posterior central gyrus,right dorsolateral frontal gyrus,and right caudate nucleus.In the functional connection(FC)of the default network,the areas of weakened FC in the AD group were the left lower cerebellum,the left inferior temporal gyrus,the left superior temporal gyrus,the right fusiform gyrus,and the right inferior temporal gyrus.Compared with the SCD group,the weakened brain area of the FC group was the right central back.Compared with the MCI group,the AD group had a weakened brain area with the right middle gyrus.Compared with the NC group in the MCI group,the FC weakened brain regions include the left cerebellum,the left lingual gyrus,the left corner gyrus,the right middle temporal gyrus,and the right medial frontal gyrus.Compared with the SCD group,the FC in the left dorsal and lateral frontal gyrus decreased and the FC in the right temporal gyrus increased.Compared with the NC group,the SCD group had weaker FC areas,including the right inferior temporal gyrus,the right suboccipital gyrus,the right middle temporal gyrus,and the right cortex.Conclusions: With the progress from SCD,MCI to AD,the atrophy of brain gray matter volume gradually increased,and the FC of resting default mode network decreased.Voxel-based morphometric methods can detect changes in AD brain gray matter volume,and the rs-f MRI methods can reflect changes in AD brain network functional connections.These two analysis methods contribute to the early clinical diagnosis of AD and are expected to become biomarkers for AD diagnosis and provide imaging indicators for monitoring AD disease progression.