Amyloid accumulation in Down syndrome measured with amyloid load

Introduction: Individuals with Down syndrome (DS) show enhanced amyloid beta (Aβ) deposition in the brain. A new positron emission tomography (PET) index of amyloid load (Aβ_L ) was recently developed as an alternative to standardized uptake value ratios (SUVrs) to quantify Aβ burden with high sensitivity for detecting and tracking Aβ change.¹.

Methods: Aβ_L was calculated in a DS cohort (N = 169, mean age ± SD = 39.6 ± 8.7 years) using [C-11]Pittsburgh compound B (PiB) PET imaging. DS-specific PiB templates were created for Aβ carrying capacity (K) and non-specific binding (NS).

Results: The highest values of Aβ carrying capacity were found in the striatum and precuneus. Longitudinal changes in Aβ_L displayed less variability when compared to SUVrs.

Discussion: These results highlight the utility of Aβ_L for characterizing Aβ deposition in DS. Rates of Aβ accumulation in DS were found to be similar to that observed in late-onset Alzheimer's disease (AD; ≈3% to 4% per year), suggesting that AD progression in DS is of earlier onset but not accelerated.