NEFL and Parkinson disease: NfL positively correlated with pSer129-αSyn pathology in PDD/DLB across all regions (LB count: r = 0.40, R2 = 16%, P = 0.002; pSer129-αSyn load: r = 0.36, R2 = 13%, P = 0.005), but not in the PD group (LB count: P = 0.392; pSer129-αSyn load: P = 0.910) (Fig. 4c).