NEFL and Parkinson disease: Interestingly, compared with women with PD, there were significant relationships between baseline CSF NfL levels and total UPDRS scores (β = 0.392, P < 0.001), UPDRSIII (β = 0.357, P < 0.001), mean caudate SBR values (β = −0.182, P = 0.008), and mean striatum SBR values (β = −0.165, P = 0.019) in men with PD.