IC‐P‐209: EARLY INCREASE IN TAU‐PET SIGNAL IS ASSOCIATED WITH Aβ BURDEN, CSF P‐TAU LEVELS AND COGNITION IN COGNITIVELY NORMAL LATE‐MIDDLE‐AGED ADULTS

9 individuals AD (N1⁄45; MMSE1⁄417.267), MCI (N1⁄41;MMSE1⁄426), FTD (N1⁄42; MMSE1⁄429.561), CN (N1⁄41, MMSE1⁄429); aged 56 to 70 yo. All participants had complete cognitive assessments. We observed that CSF T-tau and P-tau were highly correlated with [F]MK6240 uptake. The regions with the highest correlation were the entorhinal cortex (t-tau: R1⁄4 0.85, p 1⁄4 0.003; p-tau: R1⁄4 0.89, p 1⁄4 0.001), the temporal lobe (t-tau: R1⁄4 0.69, p1⁄4 0.03; p-tau: R1⁄4 0.81, p1⁄4 0.008), and the anterior cingulate (t-tau: R1⁄4 0.95, p < 0.001; p-tau: R1⁄4 0.89, p 1⁄4 0.001). Additionally, as expected, CSF Ab and [F]NAV4669 uptake were reversely correlated. Conclusions: The associations between CSF T-tau or P-tau with [18F]MK6240 support the concept that pair helical filament availability and monomeric forms of CSF p-tau and t-tau similarly reflects the tau pathology in vivo.