APOE and major depressive disorder: Other known risk factors for the development of Alzheimer’s disease include age >65 years, presence of the epsilon 4 allele of the apolipoprotein E (apoE) gene, female sex, diabetes mellitus, arterial hypertension, smoking, obesity, low levels of high-density lipoprotein cholesterol, hearing loss, traumatic brain damage, depression and social isolation, low physical activity, alcohol abuse, and air pollution (Knopman et al., 2021).