APP and Alzheimer disease: Our previous study demonstrated that auditory brainstem response (ABR), which reflects the function and integrity of the auditory pathway in the brainstem, had a reduction in APP/PS1 AD mice at the age of 3 months old (Liu et al., 2020), prior to the occurrence of typical AD phenotypes, such as spatial learning deficit, in this AD mouse model by the age of 6–7 months old (Reiserer et al., 2007; Ordóñez-Gutiérrez et al., 2015, 2016).