Association between deep gray matter iron deposition and clinical symptoms in Parkinson's disease: a quantitative susceptibility mapping study

Purpose: This study aimed to assess the association between motor and non-motor symptoms of Parkinson's disease (PD) and iron accumulation within the deep gray matter of the brain by Quantitative Susceptibility Mapping (QSM).

Methods: Fifty-six PD patients and twenty-nine healthy controls were recruited in this study. According to the Hoehn and Yahr (H-Y) stage score, PD patients were divided into early stage (H-Y ≤ 2) and advanced stage (H-Y > 2) groups. Specifically, the Regions of Interest (ROIs) encompassed the substantia nigra (SN), red nucleus (RN), caudate nucleus (CN), globus pallidus (GP) and putamen (PT). Meanwhile, various rating scales were used to assess the clinical symptoms of PD.

Results: Compared to healthy controls (HCs), PD patients showed a significant increase in magnetic susceptibility values (MSVs) within the SN and GP. Further comparisons indicated that the MSVs of the SN, PT, GP and CN are all higher in advanced stages than in early stages. Significant positive correlations were observed between the MSVs of the SN and scores on the UPDRS-III, HAMA, and HAMD (r = 0.310, p = 0.020; r = 0.273, p = 0.042; r = 0.342, p = 0.010, respectively). Likewise, the MSVs of the GP demonstrated notable correlations with HAMA and HAMD scores (r = 0.275, p = 0.040; r = 0.415, p = 0.001). Additionally, a significant correlation was found between the MSVs of the PT and HAMD scores (r = 0.360, p = 0.006). Furthermore, we identified a significant negative correlation between MMSE scores and the MSVs of both the PT and GP (r = -0.268, p = 0.046; r = -0.305, p = 0.022).

Conclusion: Our study revealed that QSM possesses the capability to serve as a biomarker for PD. Significant correlations were found between clinical features and the iron deposition in the nigrostriatal system.