These findings clearly define the age‐gradient changes in the autophagy–lysosome system, the endosome/lysosome system, and the SGK1/FOXO3a pathway in the hippocampus of APP/PS1 mice, providing new perspectives and clues for understanding the possible mechanisms of AD, especially the transition from compensatory to decompensated state. The gene discussed is FOXO3; the disease is Alzheimer disease.