MAPT and Alzheimer disease: CSF and plasma p-tau biomarkers are reported to rise early in the AD pathophysiological process.8,16 Tau tangle aggregation measured with PET occurs later and is strongly predictive of cognitive decline.53 In this connection, the much higher association of p-tau biomarkers with amyloidosis than tangle burden in CU individuals suggests that p-tau biomarkers may be less well-positioned to predict future cognitive decline.