APOE and Alzheimer disease: In APOE-ε4 non-carriers, QSM values of the left putamen in the AD group were negatively correlated with the MMSE (r = -0.600, P = 0.039) and MoCA scores (r = -0.620, P = 0.032), and QSM values in the bilateral putamen in the HCs group were negatively correlated with MoCA scores (Right, r = -0.542, P = 0.013) (Left, r = -0.503, P = 0.024) (Figures 4E–H).