The Postural Instability/Gait Difficulty (PIGD) subtype of Parkinson's disease (PD) has a faster disease progression, a higher risk of cognitive and motor decline, yet the alterations of structural topological organization remain unknown. Diffusion Tensor Imaging (DTI) and 3D-TI scanning were conducted on 31 PD patients with PIGD (PD-PIGD), 30 PD patients without PIGD (PD-non-PIGD) and 35 Healthy Controls (HCs). Structural networks were constructed using DTI brain white matter fiber tractography. A graph theory approach was applied to characterize the topological properties of complex structural networks, and the relationships between significantly different network metrics and motor deficits were analyzed within the PD-PIGD group. PD-PIGD patients exhibited increased shortest path length compared with PD-non-PIGD and HCs (P < 0.05, respectively). Additionally, PD-PIGD patients exhibited decreased nodal properties, mainly in the cerebellar vermis, prefrontal cortex, paracentral lobule, and visual regions. Notably, the degree centrality of the cerebellar vermis was negatively correlated with the PIGD score (r = -0.390; P = 0.030) and Unified Parkinson's Disease Rating Scale Part III score (r = -0.436; P = 0.014) in PD-PIGD patients. Furthermore, network-based statistical analysis revealed decreased structural connectivity between the prefrontal lobe, putamen, supplementary motor area, insula, and cingulate gyrus in PD-PIGD patients. Our findings demonstrated that PD-PIGD patients existed abnormal structural connectomes in the cerebellar vermis, frontal-parietal cortex and visual regions. These topological differences can provide a topological perspective for understanding the potential pathophysiological mechanisms of PIGD in PD.

Objective:To investigate the alterations of brain resting-state functional connectivity in patients with leukoaraiosis(LA), and to explore its neuropathological mechanism of cognitive dysfunction.Methods:From August 2022 to February 2023, 28 patients with LA(LA group) and 30 gender, age and education level matched normal controls(NC group) in Jiangsu Shengze Hospital affiliated to Nanjing Medical University were prospectively recruited.Mini mental state examination, trail-making test, and Stroop color-word test were used to evaluate the cognitive function of participants, rs-fMRI images were processed by DPABI V6.1 based on MATLAB R2022a.Voxel-mirrored homotopic connectivity(VMHC) values were calculated and two-sample t test were performed to compare the differences in local brain activity between the two groups.The brain regions with significant differences were selected as the seeds to calculate the functional connectivity(FC) values of the whole brain, and Pearson correlation analyses were performed to evaluate the correlation between the FC values and neuropsychological scores. Results:The VMHC values of the calcarine fissure and surrounding cortex(CAL) (x=±18, y=-63, z=15), postcentral gyrus(PoCG) (x=±39, y=-27, z=48), lingual gyrus(LING) (x=±12, y=-51, z=-6), middle occipital gyrus(x=±27, y=-75, z=24) and insula(x=±36, y=6, z=3) in the LA group were lower than those in the NC group( P<0.05). The seed points FC results showed, FC values between right CAL(CAL.R) and bilateral precuneus(PCUN), right dorsolateral prefrontal cortex(DLPFC.R) and right temporal_mid were reduced in the LA group( P<0.05); FC values between PoCG.R and left CAL, left temporal_mid and right LING were reduced too( P<0.05). Additionally, the FC value in the LA group between CAL.R and DLPFC.R was negatively correlated with the Stroop C score( r=-0.39, P<0.05). The FC value in LA group and NC group between CAL.R and DLPFC.R was negatively correlated with the Stroop C score( r=-0.48, P<0.001)and also negatively correlated with the trail making test B(TMT-B) score( r=-0.40, P<0.01), and the FC value between CAL.R and PCUN.L was negatively correlated with the TMT-B score( r=-0.45, P<0.001). Conclusion:Desynchronized interhemispheric functional connectivity and abnormal cortical circuit functional connectivity were probably associated with the underlying neural mechanisms of cognitive impairment in LA.