Elevated levels of serum NfL at baseline were associated with a significantly faster decrease in mean caudate SBR values (β = −0.033, P = 0.021), mean putamen SBR values (β = −0.018, P = 0.038), and mean striatum SBR values (β = −0.028, P = 0.01) in women with PD (Figure 2B). Here, NEFL is linked to Parkinson disease.