SNCA and orthostatic hypotension: In subjects with PD, BRS is substantially decreased, which is associated with orthostatic hypotension (Blaho et al., 2017; Gerasimova-Meigal et al., 2021), arterial stiffness, presence of central α-synuclein aggregation, cardiac sympathetic denervation, attenuated muscle sympathetic nerve activity (Sabino-Carvalho et al., 2021).