Resting-State Functional Magnetic Resonance Imaging On Early Alzheimer’s Disease And Late-Onset Alzheimer’s Disease

Objecive:Using resting-state functional magnetic resonance imaging(rs-f MRI)technology combined with independent component analysis(ICA),regional homogeneity(Re Ho)technology,and amplitude of low frequency fluctuations(ALFF)technology to investigate the differences in resting-state brain functional impairment patterns between patients with early-onset Alzheimer’s disease(EOAD)and late-onset Alzheimer’s disease(LOAD).Methods:A total of 43 patients with mild to moderate AD who attended the outpatient clinic of The First Hospital of Jilin University,from September 2020 to August 2022 were selected and divided into 20 patients in the EOAD group and 23 patients in the LOAD group according to the age limit of 65 years,and 27 cases in the age-and sex-matched cognitively normal control group without complaints of cognitive dysfunction,including 15 persons in the young normal control group(YNC)aged <65 years old and 12 persons in the older normal control group(ONC)aged ≥ 65 years old.General clinical data,University of Pennsylvania Smell Identification Test(UPSIT),neuropsychological measures,and imaging data were collected from the patients.Whole brain MRI data acquisition was performed on all study subjects,including T2 WI,3D-T1 WI,and rs-f MRI functional image data.Re Ho,ALFF processing was performed after image pre-processing using DPARSFA software based on Matlab R2016 a platform.Independent component analysis was performed using GIFT software based on the Matlab R2016 a platform.Independent samples t-test was used to analyze the differences between groups using dpabi software as well as SPM12 software for the four data age-matched two by two groups,using GRF correction,setting voxel P value: p < 0.001 and GRF correction cluster P value: p < 0.05.Statistically significant brain regions where the clumps were located,clump size,peak point MNI coordinates,and T-values were recorded,and the differences in local functional coherence,local brain activity intensity,and intra-and inter-network functional connectivity impairment patterns between the EOAD and LOAD groups and their age-matched controls were compared.Results:1.Neuropsychological assessment revealed that the EOAD and LOAD groups were statistically worse than the age-and sex-matched cognitively normal controls in most cognitive domains such as recall and structural ability on the UPSIT,AVLT,MMSE,and MOCA ratings(P < 0.05).The EOAD group had poorer attention scores compared to the YNC group compared to the LOAD group,matched for gender,education,and cognitive domain measure scores,and the difference was statistically significant(p < 0.05).the LOAD group had poorer AVLT scores compared to the EOAD group,and the difference was statistically significant(P < 0.05).2.Comparison by ICA analysis revealed that the EOAD group had diminished intra-network functional connectivity and no enhanced intra-network functional connectivity within several RSNs compared with the YNC group.The brain regions with reduced connectivity mainly included: the left inferior parietal marginal angular gyrus of the LFP;the left middle frontal gyrus and superior frontal gyrus of the DMN;the left precuneus,cingulate gyrus,and left middle temporal gyrus of the p DMN;and the right insula of the SN.Compared with the ONC group,the LOAD group had both reduced and enhanced functional connectivity within the network in the RSNs,where the brain regions with reduced functional connectivity were mainly included.Bilateral cingulate gyrus in the p DMN;brain regions with enhanced functional connectivity mainly included the left parietal lobe in the DAN and the left medial temporal lobe in the SN,where both enhanced and diminished intra-network functional connectivity existed in the right inferior parietal limbic gyrus in the RFP.Compared with young controls,EOAD showed enhanced negative functional connectivity between SN and LFP and diminished negative functional connectivity between SN and p DMN;LOAD showed enhanced positive functional connectivity between p DMN and l VN compared with older controls.3.Comparison by Re Ho analysis revealed that patients in the EOAD group had reduced local functional coherence in the bilateral precuneus,left inferior parietal lobule,and right superior frontal gyrus compared with young controls.LOAD patients in the LOAD group had reduced local functional coherence in the bilateral middle temporal gyrus,parahippocampal gyrus,bilateral middle frontal gyrus,bilateral supplementary motor areas,and dorsolateral superior frontal gyrus compared with elderly controls,and in the left The local functional coherence was enhanced in the subfrontal gyrus of the insula and the right cingulate gyrus.4.Comparison by ALFF analysis revealed that local brain activity was reduced in the resting state in the bilateral precuneus,left inferior parietal marginal gyrus,and right middle frontal gyrus in the EOAD group compared to the young control group.LOAD was reduced in the resting state in the corpus callosum,left cingulate gyrus,left medial superior frontal gyrus,and left middle frontal gyrus in the LOAD group compared to the elderly control group,and in the supplementary motor area.In the LOAD group,local brain activity was reduced in the corpus callosum,left medial cingulate gyrus,left medial superior frontal gyrus,and left middle frontal gyrus at rest and enhanced in the supplementary motor area at rest.Conclusions:1.The attention span of typical amnestic EOAD patients is significantly worse than that of young controls but not in LOAD patients;cognitive domains such as memory consolidation and extraction are more severely impaired in LOAD patients compared to EOAD patients.2.In the brains of EOAD patients,the DMN,especially the precuneus,has selective function and morphological vulnerability.DMN dysfunction may be a reliable neuroimaging biomarker;3.EOAD and LOAD patients have different patterns of intra-and inter-network functional connectivity,local activity coherence,and local activity impairment at rest,and LOAD patients have neurological compensatory responses to functional impairment.