Fig. 2

PD patients showed lower DAT availability in the caudate (p < 0.001) and putamen (p < 0.001) compared to HC. Current coffee consumers showed a tendency of lower DAT availability in the caudate than former/never coffee consumers in both PD patients and HC. In PD patients, there were significant differences in DAT availability in the caudate (p = 0.008) across three PD subgroups. Specifically, post hoc tests showed that current coffee consumers had significantly lower DAT availability in the caudate than former coffee consumers (p = 0.01) and never (p = 0.022) coffee consumers. In HC, there were significant differences in DAT availability in the caudate (p = 0.031) across three HC subgroups. Specifically, post hoc tests showed that current coffee consumers had significantly lower DAT availability in the caudate than former coffee consumers (p = 0.022) coffee consumers. PD-CC, current consumers of PD patients; PD-FC, former consumers of PD patients; PD-NC, never consumers of PD patients; HC-CC, current consumers of healthy controls; HC-FC, former consumers of healthy controls; HC-NC, never consumers of healthy controls; SBR, striatal binding ratios. **Bonferroni corrected; *Bonferroni uncorrected