SLC6A3 and Cognitive impairment: Our findings are in line with the previous studies on de novo PD patients of Siepel and Bronnick (2014) using the same neuroimaging technique that found a positive association between total striatal dopamine transporter binding and attention/executive deficits (but not with memory or visuospatial ones) and of Chung et al. (2018) using 18F-FP-CIT PET scan, concluding that DAT availability in the caudate is an important determinant of PD-related cognitive impairment able to discriminate MCI from normal cognition.