Mediation analysis for integrating motor symptoms of Parkinson's disease, cognitive function, and gait characteristics.

Background: In Parkinson's disease (PD) patients, the severity of motor symptoms is closely related to the degree of gait disorder and cognitive impairment; notably, the latter also exhibits a significant correlation with gait disorder. Evidently, there exists a complex relationship between motor symptoms, cognitive function, and gait characteristics. Methods: This study aims to conduct an in-depth analysis of the relationships among MDS-UPDRS III score, MoCA score, and gait parameters by constructing a mediation model. Results: We found that a higher MDS-UPDRS III score was associated with a smaller plantar dorsiflexion angle, slower velocity, and worse swing phase symmetry, and these associations were not mediated by the MoCA score. Age was a confounder in the relationship between MDS-UPDRS III score, MoCA, and velocity. A higher MDS-UPDRS III score was associated with shorter stride length, and this association was partially mediated by the MoCA score. Conclusion: The results indicated that, when analyzing plantar dorsiflexion angle and swing phase symmetry in PD patients, the influence of motor symptoms was dominant; when analyzing stride length, motor symptoms and cognitive function need to be considered simultaneously; when analyzing velocity, the influence of motor symptoms and age should be focused on.