APOE and depressive disorder: The variables of interest are the Mini-Mental State Examination (MMSE), Clinical Dementia Rating Sum of Boxes (CDRSB), hippocampus volume, Amyvid Positron Emission Tomography (AV PET), Geriatric Depression Scale (GDS), and variables to correct for possible confounding (age, biological sex, education, and APOE ε4 allele presence).