SLC1A2 and Parkinson disease: Between the PD-RBD and PD-nRBD groups, there was no significant difference in plasma levels of NDE VGLUT-1 (P = 0.713), while plasma levels of NDE EAAT-2 were significantly lower in the PD-RBD group than in the PD-nRBD group (P = 0.012) (shown in Figure 3).