APP and Alzheimer disease: Activated astrocytes that result from insults and pathological conditions such as AD display higher levels of APP and/or its processing enzymes, which may enhance the generation of Aβ peptides (Hartlage-Rübsamen et al., 2003; Kodam et al., 2010, 2019; Miake et al., 1999; Nadler et al., 2008; Nagele et al., 2003; Thal et al., 2000).