Abnormal insulin receptor signaling and increased risk of Alzheimer’s disease. IRS Insulin receptor substrate, PtdIns 3K phosphatidylinositol 3 kinase, GSK-3 glycogen synthase kinase 3, APP amyloid precursor protein, Aβ beta amyloid, Akt serine/threonine protein kinase, upward arrow indicates increase and downward arrow indicates decrease