Plasma Alzheimer's disease biomarker relationships with incident abnormal amyloid PET.

Introduction: Limited data exist on the utility of plasma biomarkers to predict incident abnormal amyloid positron emission tomography (PET). In this study we evaluate the association of plasma Alzheimer's disease (AD) biomarkers with amyloid PET progression among initially amyloid PET negative (A-) individuals.

Methods: We included 290 A-, cognitively unimpaired Mayo Clinic Study of Aging participants. We estimated the association of each baseline plasma biomarker with progression from A- to A+ and with rate of amyloid PET change.

Results: Interquartile range differences in amyloid beta 42/40, percent phosphorylated tau 217 (%p-tau217), and Amyloid Probability Score 2 were associated with 1.29 (P = 0.09), 1.38 (P < 0.001), and 1.20 (P = 0.05) increases, respectively, in the hazard of progression from A- to A+ and 0.27 (P = 0.16), 0.50 (P = 0.007), and 0.28 (P = 0.15) Centiloid/year increases, respectively, in annual rate of amyloid PET change.

Discussion: Plasma %p-tau217 may be a useful screening tool to enrich for participants with increased likelihood of progressing from normal to abnormal amyloid PET in a primary prevention trial.

Highlights: Plasma phosphorylated tau 217 was associated with amyloid positron emission tomography progression, negative to positive. The associations were weaker for amyloid beta 42/40 and Amyloid Probability Score 2. Age and apolipoprotein E ε4 carriership were also important predictors. These markers may be useful for enrichment of a primary prevention trial.