MAPT and early-onset autosomal dominant Alzheimer disease: CSF amyloid beta 1-42 (Aβ42), total tau (T-tau) and phosphorylated tau181 (P-tau181) and 11C Pittsburgh Compound B, florbetapir and florbetaben PET for Aβ pathology are now well validated for Alzheimer’s disease with 85–95% sensitivity and specificity (Zetterberg and Bendlin, 2020).