Fig. 1.

Neuropathologic evaluation of global tau and amyloid-β scales with plasma p-tau levels. We observed a strong association between the global tau scale (Braak stage [25]) and both p-tau181 (A) and plasma p-tau217 (C) across all cases studied. Visual inspection of graphs suggests a biological effect in plasma p-tau elevation between Braak stages III-IV (A, C). We observed an even stronger relationship between the global amyloid scale (Thal phase [26]) and p-tau181 (B), with the strongest association observed between Thal phase and plasma p-tau217 (D). Visual inspection of graphs suggests a biological effect in plasma p-tau elevation between Thal phase 3–4 (B, D). P-tau181 (A-B) and p-tau217 (C-D) were examined across all individuals studied with AD shown as triangles, PA as diamonds, and primary tauopathies as circles. Spearman correlation and corresponding significance displayed. Case with high creatinine was not included. Trendline with 95% confidence interval was computed from a linear model. Data presented are Spearman correlation and corresponding significance. Acronyms: AD Alzheimer’s disease, AGD argyrophilic grain disease, MSD meso scale discovery, PA pathological aging, PART primary age-related tauopathy, pg/mL picograms per milliliter, PSP progressive supranuclear palsy, p-tau phosphorylated tau for plasma levels