Brain Functional Magnetic Resonance Study Of Early Hemiparkinsonian Disease And Mild Alzheimer 's Disease

Part1Interhemispheric functional connectivity changes inearly Parkinson’s disease with the symptom asymmetryPurpose：This study used resting-state functional magnetic resonance imaging(rs-fMRI) homotopy technique called voxel-mirrored homotopic connectivity(VMHC) to investigate changes in the interhemispheric coordination integrityamong patients with hemi-parkinsonism．Methods： Sixteen Parkinson’s disease (PD) patients with right body side motorsymptom onset (RPD),15patients with left side onset (LPD), and19age-,gender-, and education-matched healthy controls (HC) were included in thisstudy. We performed voxel-mirrored homotopic correlation (VMHC) analyses onRS-fMRI data of these participants（P<0.05, corrected with AlphaSim）.Exploratory linear correlations analyses were performed between the VMHC ofregions showing significant group differences and the clinical features ofLPD or RPD patients.Moreover, voxel-based morphometry (VBM) was performedand analysis of covariance (ANCOVA) was used to assess structuralabnormalities.Results： Compared with HCs, patients with LPD had significantly reduced VMHCin visual regions, sensorimotor regions, and in the cerebellar cortex.Patients with RPD exhibited decreased VMHC in the prefrontal cortex andsensorimotor regions. Both LPD and RPD groups had increased VMHC insubcortical regions. When compared with the RPD group, the LPD group displayeddecreased VMHC in the visual regions, sensorimotor regions and increased VMHCin the supramarginal gyrus; ROI-based correlation analyses indicated that, in the LPD group, the VMHC in the inferior occipital gyrus and the postcentralgyrus was negatively correlated with the BDI-II scores (r=-0.58, p=0.02;r=-0.59, p=0.02), and positively correlated with the MMSE scores (r=0.56,p=0.03;(r=0.52, p=0.05). In the RPD group, we found a positive correlationfor the VMHC in the supramarginal gyrus with the illness duration (r=0.56,p=0.02) and for the VMHC in the postcentral gyrus with the MMSE (r=0.53,p=0.03).Conclusion：The differential pattern of deficits in the interhemisphericcoordination integrity in hemi-parkinsonism reflected by VMHC may provideinsights into the neurological pathophysiology underlying the asymmetry ofsymptom appearance in PD. Part2Investigation of functional networks changes in patientswith mild Alzheimer’s Disease using degree centralityObjective：To investigate the value of degree centrality(DC), a vovelresting-state fMRI parameter, in the voxel-wise whole-brain functionalnetworks analysis for mild AD patients and aMCI patients as compared to normalcontrols.Methods：12cases with mild AD,12cases with aMCI, and15normal agingvolunteers as control subjects were recruited. Their cognitive functions wereevaluated by the minimental state examination(MMSE)and other clinical scales.The resting-state BOLD-fMRI data were acquired and preprocessed. Analysisof DC maps changes between the2patient groups and the control group wereperformed by Two sample t test.(threshold at P＜0.05).Results： Relative to the control group, patients with mild AD showedsignificantly reduced DC value in left orbital frontal gyrus, left middlefrontal gyrus, left inferior frontal gyrus, left posterior cingulate andright posterior cingulate. In aMCI, significantly reduced DC value was foundin right precuneus, left cuneus, right cuneus, right superior occipital gyrus,right middle occipital gyrus. Interestingly, increased DC value was observedin left hippocampus, left side of the corpus callosum.Conclusion： Our results showed that DC value had changed in some region ofbrain between the2patient groups and the control group. It indicated DC,as a vovel resting-state fMRI parameter in the voxel-wise whole-brainfunctional networks, may be an appealing alternative approach for further pathologic and neuropsychological studies of AD.