Comparison of accumulation rates of beta-amyloid tracers and their relationship with cognitive changes

We aimed to compare amyloid-β (Aβ) accumulation rates between different tracers and investigate whether the relationship between changes in Aβ uptake and cognitive decline varies depending on tracer type. Two cohorts were analyzed: (1) a head-to-head longitudinal cohort using ¹⁸F-Florbetaben (FBB) and ¹⁸F-Flutemetamol (FMM) tracers (n = 13), and (2) separate longitudinal cohorts for each tracer (n = 174 for both FMM and FBB), matched by propensity score. Aβ uptake was measured using regional direct comparison of Centiloid (rdcCL) values. In the head-to-head cohort, subtracting changes in FMM rdcCL from FBB rdcCL yielded median values above zero in all regions except the cingulate. In the individual tracer cohorts, FBB rdcCL showed faster accumulation than FMM rdcCL in all cortical regions except the striatum (β [SE] = - 2.49 to - 1.56 [0.47-0.54], p < 0.001). Mini-Mental State Examination changes were associated with annualized FMM rdcCL changes in the temporal cortex (p = 0.02) and striatum (p = 0.01); however, no such differences were found in the FBB cohort. Our findings suggest that longitudinal Aβ positron emission tomography studies should consider the specific characteristics of tracers depending on the context of use.