MAPT and Alzheimer disease: However, three features consistent with disease modification were observed in this trial: (1) no return to the placebo level of the treated participants with cessation of therapy; (2) effects on biomarkers (Aβ, p-tau) considered important features of fundamental AD biology; and (3) persistent change in the trajectory of the illness that, generally, correlate with disease biomarkers and that supports modification of the underlying pathophysiology of the disease [25–27].