GRM5 and Alzheimer disease: Nerve growth and repair in AD are associated to design drugs that act as gamma secretase inhibitor, Aβ inhibitor, APOE modification, presenilin gene function (27) or antagonist for cell membrane protein, metabotropic glutamate receptor 5 (mGluR5),that recently reveals by Ji Won Um and his team (28), restoring in memory, learning, and synapse density in AD patients.