Structural network topology correlates with cognitive impairment in Parkinson's disease

In patients with Parkinsons disease (PD), cognitive impairment is common and substantially exacerbates disease severity. The objective of this study is to investigate whether cognitive decline affects disease severity and whether structural network disruption contributes to cognitive impairment in PD patients. PD patients (n = 146) receiving structural and functional magnetic resonance imaging from Parkinsons Progression Markers Initiative (PPMI) database were included. Based on the scores of Symbol Digit Modalities Test (SDMT), patients were classified into lower quartile group (SDMT score rank: 0%[~]25%), interquartile group (SDMT score rank: 26%[~]75%), and upper quartile group (SDMT score rank: 76%[~]100%) according to their SDMT score quartiles to assess how cognitive function shapes disease manifestations and brain network topology. Patients in the lower quartile group exhibited more severe motor symptoms, non-motor symptoms, and striatal dopamine depletion compared to interquartile group and upper quartile group. In addition, they also showed impaired structural network topology both at global and local levels compared to interquartile group and upper quartile group. Furthermore, different nodal network metrics in structural network contributed to cognitive and motor impairment of PD patients. Taken together, PD patients with worse cognitive function exhibited more severe motor and non-motor symptoms and aberrant structural network metrics were associated with both cognitive and motor decline of PD patients.