APOE and Alzheimer disease: 1. Key metabolic pathways related to AD were identified, such as PI3K-Akt signaling pathway, aminoacyl-tRNA biosynthesis, fat digestion and absorption, primary bile acid biosynthesis, etc, with rich factors ranging from 0.2 to 1.0.2. The expression and correlation of core genes (APOC1, APOE, NPC2) and metabolites in metabolic pathways were analyzed; component analysis showed the distribution characteristics of these molecules.