APOE and major depressive disorder: β-Amyloid plaque formation and aggregation,2 apolipoprotein E (Apo E) gene along with various environmental factors3 could be involved in the AD pathogenesis and additional risk factors; like vascular diseases, type-2 diabetes, traumatic brain injury, epilepsy, depression, smoking, diet, physical exercise, and alcohol consumption4 could be involved in the dementia pathogenesis.