Structural and functional brain abnormality patterns in patients with Parkinson’s disease: clinical correlations and implications

Objective: To investigate differences in gray matter volume (GMV) and regional homogeneity (ReHo) between patients with Parkinson’s disease (PD) and healthy controls (HC), analyze alterations in functional connectivity (FC) based on these abnormal regions, and explore the relationship between these neuroimaging markers and cognitive performance as measured by the Montreal Cognitive Assessment (MoCA). Materials and Methods: A total of 41 PD patients and 26 healthy controls underwent clinical assessments, high-resolution 3D T1-weighted structural MRI, and resting-state functional MRI (rs-fMRI). Voxel-based morphometry and ReHo analysis were used to identify regions with significant structural and local functional differences. These regions were defined as regions of interest (ROIs), and seed-based FC analysis was performed to assess connectivity alterations. Two-sample t-tests were used to compare GMV, ReHo, and FC values between groups. Spearman correlation analysis was conducted to explore associations between imaging metrics and MoCA scores in the PD group. Results: Compared to healthy controls, PD patients showed significantly reduced GMV in the left superior cerebellum, left prefrontal cortex, and right putamen. GMV in the left superior cerebellum was positively correlated with MoCA scores (r = 0.315, p = 0.045). Decreased ReHo was observed in the right medial superior frontal gyrus and left dorsolateral prefrontal cortex, although these changes were not significantly correlated with cognition. FC was reduced in brain regions with GMV atrophy and lower ReHo, including the left superior cerebellum, prefrontal cortex, and superior frontal gyrus. Notably, FC in the left dorsolateral prefrontal cortex was significantly positively correlated with MoCA scores (r = 0.380, p = 0.014). Conclusion: Parkinson's disease (PD) patients show decreased regional functional homogeneity and substantial gray matter atrophy. Structural and functional neuroimaging may be used to better clarify the possible reasons of cognitive impairment in Parkinson's disease by identifying GMV and FC abnormalities in specific brain regions.