MAPT and Alzheimer disease: Increasingly, SCCs are considered to be the earliest detectable prodromal stage of AD (Sperling et al., 2011; Mitchell et al., 2014) and have been linked to the presence of AD biomarkers like amyloid plaques in the brain (Jack et al., 2013), tau proteins in cerebral spinal fluid (Amariglio et al., 2015), and cerebral atrophy and/or hypometabolism (Mosconi et al., 2008; Striepens et al., 2010).