APP and Alzheimer disease: Alzheimer’s disease (AD) is the most common neurodegenerative disorder characterized by a progressive decline in memory and other cognitive functions.It is estimated that over 35 million people worldwide suffered from the disease and AD-related healthcare cost was$604 billion in 2010 alone [1], [2].While early-onset AD can be caused by gene mutation in APP, presenilin1 or presenilin2, it only accounts for less than 5% of all AD cases [3].