APOE and major depressive disorder: One of the cross-sectional studies from the MCSA has demonstrated an association between glucose hypometabolism on FDG-PET and depression measured on the NPI-Q (OR = 2.12; 95%CI, 1.23–3.64; P ≤ 0.05), especially in apolipoprotein E4 (ApoE4) carriers (OR = 2.59; 95%CI, 1.00–6.69; P = 0.05) [52].