The protein level of HDAC3 was significantly increased in the hippocampal nuclei of 6‐ and 9‐month‐old APP/PS1 mice (P = 0.008 and P < 0.001, respectively; Fig. 1E,F), which indicated that the increase in HDAC3 in the nuclei might be associated with the pathogenesis of AD. This evidence concerns the gene PSEN1 and Alzheimer disease.