Brain Structure And Function In Different Subtypes Of Parkinson’s Disease Based On Magnetic Resonance Imaging

Parkinson’s disease(PD)is a progressive neurodegenerative disease among the elderly,presenting typical motor symptoms,such as resting tremor,rigidity and bradykinesia,as well as non-motor symptoms.According to the predominant motor symptoms,PD can be divided into an akinetic-rigid(AR)subtype and a tremor-dominant(TD)subtype.Clinical evidence has suggested that different PD subtypes have distinct clinical courses and prognoses.Indeed,relative to the TD subtype,the AR subtype tends to have a more rapid clinical progression and a higher risk for developing dementia and other mental diseases such as depression,suggesting the disparate neural bases among subtypes.We computed Local Gyrification Index(LGI)and Fractional Anisortropy(FA)from T1-weighted and diffusion-weighted MRI in 90 patients with PD(including 64 patients with the AR subtype and 26 patients with the TD subtype)and 56 healthy controls(HCs).Pairwise group contrast was performed to assess the differences in LGI and FA among the three groups.In each patient group,an intermodal correlation analysis was performed to examine the relationship between the LGI and FA for the significant regions identified in the corresponding group contrast.Compared with HCs,patients with the AR subtype showed significantly lower LGI in widespread cortical regions,including the bilateral precentral gyrus,medial and lateral orbitofrontal cortex,inferior and superior parietal lobule,precuneus,posterior cingulate cortex,cuneus and nearby visual cortices,left inferior,left anterior cingulate cortex,middle and superior temporal gyrus,right postcentral gyrus,middle and superior frontal gyrus,and right supramarginal gyrus.In patients with the AR subtype,the LGI of a significant cluster,involving the left inferior and middle frontal gyrus,was found to be correlated with the MMSE and H &Y score,respectively.We found no significant LGI changes in patients with the TD subtype compared with patients with the AR subtype and HCs.In addition,no significant correlations were found between the LGI and the clinical data of patients with the TD subtype.Compared with HCs,patient with the AR subtype showed significantly lower FA in several WM tracts,involving bilaterally the corticospinal tract,anterior thalamic radiation,inferior fronto-occipital fasciculus,inferior longitudinal fasciculus,forceps minor,forceps major,superior longitudinal fasciculus,and anterior thalamic radiation.We found no significant correlation between FA and the clinical data of patients with the AR subtype.We found no significant FA change in patients with the TD subtype compared with patients with the AR subtype and HCs.In addition,no significant correlations were found between FA and the clinical data of patients with the TD subtype.In patients with the AR subtype,the LGI of a significant cluster,involving the left inferior and middle frontal gyrus,was found to be correlated with the MMSE and H &Y score,respectively.These findings provide new evidence for the neural basis of abnormal brain function and structure in different subtypes of PD,which is beneficial to the prediction,diagnosis and treatment of PD.In addition,we made a static functional network analysis of AR subtype and TD subtype.Our results show that the standardized clustering coefficient,small-world scalar attribute,global efficiency and local efficiency of AR subtype are higher than those of normal control and TD subtype,indicating that the network transmission and information interaction ability of AR subtype are enhanced.These findings reveal the coexistence of degenerative and compensatory changes of AR subtype.This provides a new insight for understanding the pathological mechanism of Parkinson’s disease.