MAPT and Alzheimer disease: RESULTS: Of 335 A4 participants with complete biomarker data, 222 were identified as being in Biological Stage A. Among Biological Stage A CU, baseline plasma p-tau217 and amyloid-PET burden were associated with faster tau-PET accumulation and atrophy in AD-relevant regions (mean [SD] follow-up time for tau-PET: 4.2 [2.1] years and MRI: 4.2 [1.9] years), as well as faster cognitive decline (mean [SD] follow-up time for PACC: 5.7 [1.6] years) (all p < 0.05).