“…The study comprised a total of 6,057 participants, with 3,422 patients diagnosed with PD, 1,983 healthy controls, and 652 cases of APS (476 with MSA and 176 with PSP). Among these studies, 22 focused on the diagnosis of PD ( Cheng et al, 2019 ; Shinde et al, 2019 ; Wu et al, 2019 ; Xiao et al, 2019 ; Cao et al, 2020 , 2021 ; Liu et al, 2020 ; Shu et al, 2020 ; Dhinagar et al, 2021 ; Li et al, 2021 , 2022 ; Ren et al, 2021 ; Shi et al, 2021 , 2022a , 2022b ; Sun et al, 2021 , 2022 ; Zhang et al, 2021 ; Ben Bashat et al, 2022 ; Guan et al, 2022 ; Kang et al, 2022 ; Shiiba et al, 2022 ), while six studies focused on the differential diagnosis of PD and APS ( Pang et al, 2020 , 2022 ; Hu et al, 2021 ; Tupe-Waghmare et al, 2021 ; Kim et al, 2022 ; Zhao et al, 2022 ). In addition, two studies addressed the differential diagnosis of PD with or without depression ( Li et al, 2021 ; Zhang et al, 2021 ), and one study fixated on the differential diagnosis of TD and PIGD ( Sun et al, 2021 ).…”