Significant risks included older age (n = 6/10 studies19, 35, 38, 39, 40, 41, 44), poor baseline performance on cognitive tests (n = 5/7 studies36, 40, 41, 42, 43), sex (being female; n = 3/10 studies35, 38, 44), hypertension (n = 3/6 studies35, 38, 39), low educational attainment (illiteracy or primary school; n = 2/10 studies35, 36), anxiety and depression (n = 2/5 studies39, 40), history of stroke (n = 1/4 studies36), diabetes (n = 2/4 studies35, 39), and apolipoprotein E (APOE) ε4 status (n = 2/4 studies35, 39). This evidence concerns the gene APOE and major depressive disorder.