After age, sex, disease duration, and baseline MoCA scores were adjusted, higher baseline plasma GFAP levels (HR: 1.009, 95% CI [1.001 to 1.017], p = 0.033) and higher baseline UPDRS-III scores (HR: 1.107, 95% CI [1.063 to 1.153], p < 0.001) predicted a more rapid progression to postural instability in the multivariate Cox regression models (Additional file 1: Table S5). This evidence concerns the gene GFAP and Postural instability.