Here, compared with the PD-NOD group, the T-tau level in CSF from the PD-OD group significantly declined (Table 4), and the decreased T-tau level in CSF was significantly and positively correlated with the declination of DIS (Table 5), implying that the decrease of T-tau in CSF might result from the increase of T-tau in the brain and lead to DIS. This evidence concerns the gene MAPT and Parkinson disease.