COMT and Postural instability: General risk factors of PDD include older than 75 years old, PD duration of more than 10 years, UPDRS >24, H-Y stage, impairment of semantic fluency, impairment on pentagon test, genetic factors (GBA1, COMT, MAPT H1/H1, APOE4), low education level, postural instability and cerebral small vascular disease (Aarsland et al., 2001; Vasconcellos and Pereira, 2015; Hou et al., 2022; Kwon et al., 2022).