Plasma p217+tau versus NAV4694 amyloid and MK6240 tau PET across the Alzheimer's continuum

Introduction: We evaluated a new Simoa plasma assay for phosphorylated tau (P-tau) at aa217 enhanced by additional p-tau sites (p217+tau). Methods: Plasma p217+tau levels were compared to F-18-NAV4694 amyloid beta (A beta) positron emission tomography (PET) and F-18-MK6240 tau PET in 174 cognitively impaired (CI) and 223 cognitively unimpaired (CU) participants. Results: Compared to A beta- CU, the plasma levels of p217+tau increased 2-fold in A beta+ CU and 3.5-fold in A beta+ CI. In A beta- the p217+tau levels did not differ significantly between CU and CI. P217+tau correlated with A beta centiloids P = .67 (CI, P = .64; CU, P = .45) and tau SUVRMT P = .63 (CI, P = .69; CU, P = .34). Area under curve (AUC) for Alzheimer's disease (AD) dementia versus A beta- CU was 0.94, for AD dementia versus other dementia was 0.93, for A beta+ versus A beta- PET was 0.89, and for tau+ versus tau- PET was 0.89. Discussion: Plasma p217+tau levels elevate early in the AD continuum and correlate well with A beta and tau PET.

Automated summary

This study evaluated a new Simoa plasma assay for phosphorylated tau (P-tau) and found that plasma P-217+tau levels elevate early in the AD continuum and correlate well with A beta and tau PET.