Relationship between amyloid and tau levels and its impact on tau spreading

Background Previous studies have shown that Aß-amyloid (Aß) likely promotes tau to spread beyond the medial temporal lobe. However, Aß levels necessary for in neocortex is still unclear. Method 466 participants underwent imaging with [18F]MK6420 and [18F]NAV4694 (Fig. 1). scans were quantified on Centiloid (CL) scale a cut-off of 25CL abnormal (A+). Tau three regions interest (ROI) (mesial (Me); temporoparietal (Te); rest (R)) four mesial region (entorhinal cortex, amygdala, hippocampus parahippocampus) using cerebellar cortex as reference region. Regional thresholds established 95%ile cognitively unimpaired A- subjects. The prevalence (T+) along continuum was determined. Result plots T+ 2) show earlier greater increase area compared neocortex. Prevalence low but associated level between 10-40 CL reaching 23% Me, 15% Te 11% R. Between 40-70 CL, subjects per increased four-fold faster at 70 64% 51% 37% In 3), there no R below 50 CL. highest found entorhinal 40% 40 80% 60 Conclusion Outside cortical PET are rarely Above accelerates all areas. Moderate required before neocortical becomes detectable.