APP and early-onset autosomal dominant Alzheimer disease: Even in autosomal dominantly inherited Alzheimer’s disease (ADAD), where the course of Alzheimer’s disease development is strongly determined by mutations in genes encoding presinilin-1 (PSEN1), presenilin-2 (PSEN2) or amyloid precursor protein (APP), the cognitive status remains relatively stable in some patients despite advanced levels of amyloid-β and tau pathology (Lim et al., 2016).