PSEN2 and Impaired glucose tolerance: A small percentage of cases of AD are associated with genetic factors, in the form of autosomal dominant inheritance of the genes producing amyloid precursor protein (APP), presenilin 1(PSEN1), and presenilin 2 (PSEN2), and is called the familial form (FAD) of AD [5], while the sporadic form (SAD) is associated with environmental risk factors, such as cardiovascular disease, stroke, cancer, impaired glucose tolerance, and diabetes mellitus (DM) [6,7,8].