NEFL and Parkinson disease: Therefore, this study aimed to compare six plasma biomarkers (Aβ42, Aβ40, Aβ42/40, p-tau181, GFAP, and NfL) between patients with PD and healthy controls (HCs) and investigate their association with comprehensive clinical parameters, including subitems of cognitive scales, to provide insights into the link between AD-related plasma biomarkers and the clinical presentation of cognitive impairment in PD.