GAD1 and Parkinson disease: In conclusion, the treatments that use small molecule α-synuclein aggregation therapy (ambroxol or Cu(II)ATSM) or monoclonal antibody (AFFITOPE® PD01A, and PRX002) or gene therapy (PR001A/AAV-GAD) might be promising compared to other clinical trials/therapies for the treatment of PD in future.