SLC6A3 and Parkinson disease: Our longitudinal imaging results showed that striatal and extrastriatal deficit worsened at 2-year follow-up in PD but not in SWEDD (Fig. 1D and Table 2), which is in line with previous DAT studies focusing on striatal binding (Batla et al., 2014, Lee, et al., 2021, Marek et al., 2014, Marshall et al., 2006).