The current study used wild‐type (WT), ApoE‐knockout (ApoE‐KO), ApoE3‐targeted replacement (ApoE3), and ApoE2‐targeted replacement (ApoE2) mice to investigate whether total ApoE, full‐length ApoE, or ApoE fragments play a role in the presence and severity of Tau phosphorylation and cognitive impairment in P6 mice under sevoflurane anesthesia. The gene discussed is APOE; the disease is Cognitive impairment.