The strongest evidence causally linking cholesterol to AD is provided by experimental studies showing that adding or reducing cholesterol alters amyloid precursor protein (APP) and Aβ peptide levels (McLaurin et al., 2003; Wood et al., 2003; Lin et al., 2009; Banerjee et al., 2021; Hashemi et al., 2022). The gene discussed is APP; the disease is Alzheimer disease.