However, the overall PD group had significantly higher serum NfL levels (mean: 13.88 pg/ml, p = 0.001), higher Movement Disorders Society Unified Parkinson’s Disease Rating Scale (MDS-UPDRS) III scores (mean: 21.25, p < 0.001), and lower Montreal Cognitive Assessment (MoCA) scores (mean: 26.69, p < 0.001) compared to HC. Here, NEFL is linked to Parkinsonism.