Structural network topology mediated cognitive impairment in Parkinson's disease

Cognitive impairment (CI) is one of the most prominent non-motor symptoms in Parkinsons disease (PD). How brain network abnormalities contribute to CI in PD patients remain largely unclear. The goal of this study is to explore whether aberrations of brain network topology were causally associated with cognitive decline in PD patients. PD patients receiving magnetic resonance imaging from Parkinsons Progression Markers Initiative (PPMI) database were specifically selected. According to the scores of Montreal Cognitive Assessment (MoCA), PD patients were classified into CI+ group (MoCA score [≤] 25) and CI-group (MoCA score > 25) to investigate whether clinical features and brain networks were significantly different between two groups. Mediation analysis was utilized to evaluate whether brain network alterations contributed to CI in PD patients. We revealed CI + group exhibited more severe non-motor symptoms compared to CI-group. In addition, age, excessive daytime sleepiness, and depressive symptoms were found to be significantly associated with CI of PD patients. Moreover, CI+ group exhibited statistically different local topological properties in structural network compared to CI-group. Furthermore, differential local topological metrics in structural network meditated the effects of age, excessive daytime sleepiness, and depression on cognitive decline of PD patients. Taken together, out study suggested that PD patients with CI exhibited notable disturbances of structural network topology, which mediated negative associations between of age, excessive daytime sleepiness, depression and cognitive decline of PD patients.