MAPT and Alzheimer disease: This strong association between plasma p‐tau‐181 and Aβ deposition is in line with previous published studies in AD, showing that plasma p‐tau‐181 is a sensitive predictor of elevated brain Aβ on PET at preclinical stages, before observing widespread tau aggregates in the neocortex.28, 30, 31, 32, 33, 34