PSEN2 and Alzheimer disease: There are many risk factors for AD and, among others, they are age, genetics (APOE-e4, Down syndrome, genetic mutations of the APP gene and genes for presenilin-1 and presenilin-2, and a first-degree relative with AD), smoking, obesity, hypertension, high cholesterol levels, diabetes, diet, low physical activity, lower socioeconomic status, and poor sleep quality.