Analyses On The White Matter Morphology In Different Subtypes Of Parkinson’s Disease

Parkinson’s disease is the second most common neurodegenerative disease,whose main symptoms are divided into motor symptoms and non-motor symptoms.According to the different motor symptoms clinically manifested,Parkinson’s disease is mainly divided into akinetic-rigid(AR)dominant subtype and tremor dominant(TD)subtype.Some studies have shown that AR subtype develop faster than TD subtype and have a higher risk of developing other serious neurological diseases,such as dementia,etc.These results indicate that the two subtypes have different pathological basis.The purpose of this study was to investigate the morphological changes of white matter structures in Parkinson’s disease patients with AR subtype and TD subtype.Therefore,this study uses multimodal magnetic resonance data of 90 patients with Parkinson’s disease and 56 healthy controls and analyzes different subgroups by two analysis methods-Director Field Analysis(DFA)and Fixel-based Analysis(FBA),to explore the structural and morphological changes of white matter fibers.In this study,four indicators in DFA were calculated,including bend,splay,twist and distortion.Compared with the healthy control group,the patients with AR subtype and TD subtype showed significant decreases in the four indicators,and the areas where the indicators decreased mainly included bilateral internal capsule,corona radiata,corpus callosum,and right superior longitudinal fasciculus.There were no significant indicator changes between AR subtype and TD subtype.In addition,this study found that bend in the difference area was positively correlated with MoCA and MMSE scores,negatively correlated with UPDRS-Ⅲ scores,and twist was positively correlated with MoCA scores.And this study also found correlation between distortion and changes in brain morphology.Besides,FBA indicators such as fiber density(FD),fiber bundle cross section(FC)and fiber density and cross section(FDC)were calculated in this study.Compared with the healthy control group,the FD,logFC and FDC of the AR subtype group were all decreased,and the areas where the indicators decreased included the corticospinal tract,internal capsule,genus of the corpus callosum,right inferior longitudinal fasciculus and right optic radiation.There was no significant change in these three indicators of the TD subtype group compared with healthy control group.The patients with AR subtype showed reduced FD,log-FC,and FDC in the right corticospinal tract and internal capsule compared with the patients with TD subtype.In addition,FDC in the genu of the corpus callosum was negatively correlated with UPDRS-Ⅲ and H&Y scores,and FDC in the right inferior longitudinal fasciculus was negatively correlated with UPDRS-Ⅲ scores.Effective classification of motor subtypes in Parkinson’s disease by logistic regression models using differences in FBA indices between the two subtypes as features.These results suggest that specific alterations in white matter fiber structure in Parkinson’s disease are associated with a motor phenotype,providing new insights into the pathogenesis and pathology of Parkinson’s disease subtypes.