MAPT and Alzheimer disease: In agreement, a high-fat diet that elevates glucose and corticosterone in mice activates serum-glucocorticoid-regulated kinase 1 (SGK1) and GSK3β to promote tau hyperphosphorylation, neurodegeneration, and impaired spatial learning and memory in these mice, and SGK1 is also activated in the hippocampus of human brains with AD (27).