Research Of Brain Resting State Functional Magnetic Resonance Imaging In Tremor Dominant Parkinson’s Disease

Research background and purpose:Parkinson’s disease（PD）is the second most common chronic neurodegenerative disease in middle-aged and elderly individuals.Clinically,based on its main motor symptoms,it is usually divided into tremor-dominant（TD）,postural instability/gait difficulty（PIGD）,and mixed types.Compared to PIGD-PD patients,TD-PD patients exhibit lighter cognitive dysfunction,shorter disease duration,and better prognosis.Some PD patients may present initially with TD,which may transform into PIGD as the disease progresses and other complications may appear in the later stages.Some studies have suggested that PD patients of different subtypes may have different neuropathophysiological characteristics.This study compared the amplitude of low frequency fluctuation（ALFF）,regional homogeneity（Re Ho）,and functional connectivity（FC）based on the region of interest（ROI）between the TD-PD group and the healthy control（HC）group,in order to explore changes in brain functional activity in TD-PD patients,and to help understand the possible neuropathological mechanisms of TD-PD.Materials and Methods:A total of 48 PD patients diagnosed at the Second People’s Hospital of Yibin from December 2019 to March 2021 were collected,and they were evaluated using the Movement Disorder Society-Unified Parkinson’s Disease Rating Scale（MDS-UPDRS）and Mini-Mental State Examination（MMSE）as well as MRI scans.Based on the ratio of average tremor-related scores to average posture and gait-related scores in Part II and Part III of the MDS-UPDRS,as well as the MRI quality control to exclude subjects who did not meet the requirements,a total of 23 eligible TD-PD patients were included,of whom11 were male and 12 were female,with an age of 62.96±9.56 years and an education level of 7.57±1.99 years.In addition,21 healthy controls matched with the TD-PD group in terms of demographic data were recruited from the community,including 11 males and10 females,with an age of 57.67±8.98 years and an education level of 8.14±2.71 years.The ALFF and Re Ho differences between TD-PD group and HC group were compared using SPM12 and RESTplus toolboxes on Matlab R2014b platform respectively.The ALFF and Re Ho differences were used as ROI to analyze the FC changes with the whole brain.The ALFF values,Re Ho values and FC values of the different brain regions in TD-PD group were extracted,and Pearson correlation was used to analyze the correlation between ALFF values,Re Ho values,FC values and the severity of tremors（tremor score）.Results:1.Compared with the HC group,the ALFF of left calcarine sulcus（extending to left lingual gyrus）（ROI1）,right dorsolateral upper frontal gyrus（extending to right middle frontal gyrus）（ROI2）,left dorsolateral upper frontal gyrus（extending to left middle frontal gyrus）（ROI3）significantly decreased in TD-PD group（Alphasim corrected;P（voxel）<0.001,P（cluster）<0.05）.2.In TD-PD group,the FC between ROI1 and right angular gyrus was increased;the FC between ROI2 and right superior parietal lobule,right temporal pole middle temporal gyrus was decreased;the FC between left ROI3 and left temporal pole middle temporal gyrus was also decreased(Alphasim corrected;P_（voxel）<0.001,P_{（cluster）}<0.05).3.Compared with the HC group,the Re Ho of left posterior cingulate（ROI4）,right superior frontal gyrus（ROI5）,left angular gyrus（ROI6）significantly increased in TD-PD group(Alphasim corrected;P_（voxel）<0.001,P_{（cluster）}<0.05).4.In TD-PD group,the FC between ROI4 and left superior occipital gyrus was decreased;the FC between ROI5 and right cerebellum posterior lobe,left hippocampus（extending to left parahippocampal）,left middle temporal gyrus,left angular gyrus were increased;the FC between ROI5 and left frontal lobe Sub-Gyral was decreased;the FC between ROI6 and right superior frontal gyrus was increased（Alphasim corrected;P（voxel）<0.001,P（cluster）<0.05）.5.The FC value of ROI5 and left angular gyrus,left hippocampus（extending to left parahippocampal）are negatively correlated with the tremor score（P<0.05）.Conclusion:This study utilized resting-state ALFF and Re Ho,as well as the differences in ALFF and Re Ho between two groups as ROIs for the whole-brain FC method to investigate local brain region changes and brain network connectivity patterns in tremor-dominant Parkinson’s disease TD-PD patients.The study found that TD-PD patients had changes in neural functional activity in multiple brain regions,mainly involving the visual cortex,anterior sensory cortex,limbic system cortex,cerebellar posterior lobe,dorsal attention network,and default mode network,and abnormal synchronization of brain region activity was observed.Abnormalities in the function of the superior frontal gyrus and angular gyrus were found in both methods.These findings provide neuroimaging information for further exploration of the pathological mechanisms of tremor-dominant PD.This study found that in TD-PD patients,the FC values of the right superior frontal gyrus and left angular gyrus,as well as the FC values of the left hippocampus（extending to left parahippocampal）,were negatively correlated with the severity of tremors,which may be potential imaging biomarkers for the severity of tremor symptoms in TD-PD patients.