APP and Alzheimer disease: In the present study, SH-SY5Y cells transfected with the APP Swedish mutant gene and APP/PS1 transgenic mice were used as cellular and animal models of AD and were treated with a Class I HDACI (BG45) to explore the early synaptic damage in AD models and the protective effect and mechanism of BG45 against the damage caused by AD to provide new insights into clinical interventions and treatments for AD.