Altered resting-state functional connectivity and network topology in early-stage Parkinson’s disease: associations with depressive symptoms

Introduction: Parkinson's disease (PD) is one of the most common neurodegenerative disorders, affecting approximately 1–2% of people over 60 years of age worldwide. Early diagnosis of PD from other neurodegenerative diseases remains challenging due to the lack of reliable biomarkers. Further research is needed to discover sensitive and reliable biomarkers for PD. Resting-state functional magnetic resonance imaging (rs-fMRI), as a non-invasive imaging method, provides valuable information about changes in functional brain connectivity and brain networks in PD. In addition to measuring spontaneous brain activity, studies have shown that the connectivity profile within or between important brain networks is also altered and disrupted. Therefore, this study aims to investigate alterations in functional connectivity and graph-theoretical network properties in early-stage PD compared to healthy controls. Materials and Methods Structural magnetic resonance imaging (sMRI) and rs-fMRI of 35 patients with PD and 22 healthy controls, along with demographic information, and psychological test results (GD-Scale) were collected from the PPMI database. CONN software was used for preprocessing, noise removal, and extracting functional connectivity matrix and graph parameters. Finally, by extracting the functional matrix and graph parameters, the rs-fMRI images of the two PD and control groups were statistically compared. The correlation between depressive symptom severity (measured by the Geriatric Depression Scale, GDS) and rs-fMRI features was also examined. Results The statistical results of this study showed that in patients with PD, functional connectivity decreased in the left and right Postcentral Gyrus regions. At the same time, it increased in the right and left Insular Cortex regions and the left Planum Temporale. Examination of graph parameters revealed decreased global efficiency and degree centrality, but increased average path length, in the default mode network of PD patients compared to controls. Conclusion These findings suggest that rs-fMRI may reveal network-level alterations associated with early-stage PD, particularly in relation to depressive symptoms, though diagnostic applications require further validation.