Compared with results shown in baseline NfL analyses, a longitudinal 3-year increase in CSF NfL levels was also significantly associated with motor impairments, which were tested by mean caudate SBR values (β = −0.516, P < 0.001) and mean striatum SBR values (β = −0.269, P = 0.002) in PD groups. This evidence concerns the gene NEFL and Parkinson disease.