APOE and atherosclerosis: The LC-MS/MS technique was used for non-targeted lipidomics analysis to identify the differential lipid metabolites and major metabolic pathways in the prefrontal cortex and hippocampus regions, and the 16S recombinant-DNA (rDNA) amplification sequencing technique was used to study the changes of the gut microbiota in ApoE−/− mice with atherosclerosis co-depression.