Mielke MM, Frank RD, Dage JL, et al. - In this cross-sectional study involving 200 participants, researchers sought to conduct a head-to-head comparison of plasma p-tau181 and p-tau231 measured on the single-molecule array (Simoa) platform and p-tau181 and p-tau217 measured on the Meso Scale Discovery (MSD) platform on amyloid and tau positron emission tomography (PET) measures, neurodegeneration, vascular pathology, and cognitive outcomes. In total, 177 were cognitively unimpaired (CU) and 23 had mild cognitive impairment. No differences were found between the p-tau species for amyloid PET and tau PET metaregions of interest, however, among CU participants, both MSD p-tau181 and MSD p-tau217 more precisely predicted abnormal entorhinal cortex tau PET than Simoa p-tau181. MSD p-tau181 and p-tau217 and Simoa p-tau181, but not p-tau231, were linked to greater white matter hyperintensity volume and lower white matter microstructural integrity. These findings in this largely presymptomatic population point to subtle differences across plasma p-tau species and platforms for predicting amyloid and tau PET and MRI measures of cerebrovascular and Alzheimer-related pathology.