PPIB and Alzheimer disease: Therefore, the “Amyloid Cascade Hypothesis” [9,10], which postulates that the neurodegeneration in Alzheimer’s disease caused by abnormal accumulation of amyloid-β plaques in various areas of brain, has also developed into the “Amyloid-β Oligomer Hypothesis” [11], which postulates that the neurodegeneration in Alzheimer’s disease caused by abnormal accumulation of Aβ42 oligomers (Aβ42Os) in various areas of brain.