Long‐term progression of amyloid and tau biomarker profiles: Four‐year follow‐up imaging study

Abstract

AbstractBackgroundTo investigate long‐term progression of amyloid (A) and tau (T) image‐based biomarker profiles in a cohort with wide range of cognitive status.MethodIn 273 participants [96 cognitively unimpaired (CU), 106 mild cognitive impairment (MCI), and 71 AD dementia (DEM)] who completed 18F‐florbetaben and 18F‐flortaucipir PET studies for visit 1 (V1), 167 participants (62 CU, 68 MCI, and 37 DEM) completed visit 2 (V2) PET studies at two years, and subsequently 66 participants (23 CU, 33 MCI, and 10 DEM) completed visit 3 (V3) PET studies at about four years (mean 4.5 years) after the V1 study. A/T biomarker profiles were determined by using the cut‐off standardized uptake value ratios of composite regions most vulnerable to each pathology.Result5.6% (5/90) of participants converted from A‐ to A+ at V2 and 18.5% (5/27) at V3. Likewise, 4.2% (5/118) of participants converted from T‐ to T+ at V2 and 17.4% (8/46) at V3. In comparison with lower conversion rate from T‐ to T+ in the A‐T‐ participants [2.3% (2 A‐T+ / 86 A‐T‐) at V2 and 7.4% (2 A+T+ / 27 A‐T‐) at V3], A+T‐ participants exhibited higher conversion rate from T‐ to T+ [9.4% (3 A+T+ / 32 A+T‐) at V2 and 31.6% (6 A+T+ / 19 A+T‐) at V3].ConclusionPositive conversion of A/T biomarkers occurs steadily throughout the long‐term period. Compared to A‐ individuals, positive conversion of T biomarker occurs four times more frequently in A+ individuals.