PSEN1 and Alzheimer disease: The risk factors for AD are, among others, age, genetics (APOE-e4), Down syndrome, genetic mutations involving the APP gene and genes for presenilin-1 and presenilin-2, first-degree relative with AD, smoking, midlife obesity, hypertension, high cholesterol levels, diabetes, diet, low physical activity, lower socioeconomic status, and poor sleep quality.