DRD1 and Alzheimer disease: However, compared to the control cases, there were some more apparent findings than in the previously reported data: an exceptional increase in 8‐oxo‐dG in the caudate, and decrease in the putamen; decreased 8‐oxo‐G levels, increased dopamine concentration, VMAT2, and D1R density were found both in the caudate and putamen of AD cases (Figs 7a and b; Table 2).