Age dependence of brain b-amyloid deposition in Down syndrome: An [18F]florbetaben PET study

Objective: To investigate brain β-amyloid binding in subjects with Down syndrome (DS) using [18F] florbetaben PET imaging. Methods: Thirty-nine subjects with DS (46.3 ± 4.7 years) were assessed with [18F]florbetaben PET imaging. Three blinded independent readers assessed the scans to provide a visual analysis. The primary quantitative imaging outcome was a standardized uptake value ratio (SUVR) obtained for 6 brain regions. Cognitive status was evaluated using the Dementia Screening Questionnaire for Individuals with Intellectual Disabilities (DSQIID). Results: [18F]Florbetaben uptake was correlated with age (p , 0.0001, R2 5 0.39); 90%of scans in subjects with DS aged 50 years or older (SUVR 5 1.62 ± 0.26), 53% in those aged 45 to 49 years (SUVR 5 1.43 ± 0.16), and 7%in those aged 40 to 45 years (SUVR 5 1.27 ± 0.11) were visually assessed as positive. Visual and quantitative assessments were highly related (x2 5 11.3823, p 5 0.0007; Cohen k 5 0.58). Only 2 of 34 participants were considered to have dementia by the DSQIID. Conclusions: Brain β-amyloid binding, as measured by [18F]florbetaben, increases with age in DS. Subjects with DS who have no evidence of dementia demonstrate brain β-amyloid binding in vivo, suggesting that [18F]florbetaben PET imaging may detect β-amyloid in this at-risk population