In this study, we have shown a cell-type-specific function of GPR120 in the brain, identified allosteric agonists of GPR120 from BRDs, and discovered that allosteric activation of a cell-type-specific GPR120 with ALA and EDA inhibits amyloid pathology, rescues cognition, and restores lifespan to normal levels in mouse preclinical models of AD. This evidence concerns the gene FFAR4 and Alzheimer disease.