Trajectories of plasma biomarkers, amyloid-beta burden and cognitive decline in Alzheimer's disease: A Longitudinal ADNI Study

As novel amyloid-{beta} targeted therapies emerge, plasma biomarkers have promising potential to serve as screening tools and as surrogate measures for treatment outcomes. Understanding longitudinal trajectories of these biomarkers and how their changes relate to changes in AD pathology and cognition is needed to help track treatment response and guide patient care. We analyzed data from 394 individuals in the ADNI-FNIH dataset who had plasma biomarkers available across 14 assays, A{beta}-PET scans and cognitive assessments over a 10-year period. Plasma p-tau217, regardless of the assay used, had the greatest rate of change over time. This increase was related to concurrent increase in A{beta}-PET burden only in individuals with low levels of A{beta}. The rate of p-tau217 change, rather than its baseline level, was the strongest predictor of future A{beta}-PET positivity. On the other hand, in individuals with elevated levels of A{beta}, higher rate of change in p-tau217 was associated with faster cognitive decline. These findings highlight a "dual" role of plasma p-tau217 rate of change, being either predictive of accumulating A{beta} pathology at early stages and of cognitive decline at later stages of the AD continuum.