Amyloid imaging and cognitive decline in nondemented oldest-old: The 90+Study

Background: The goal of this study was to examine cross-sectional and longitudinal associations between cognitive performance and beta amyloid (A beta) load determined by florbetapir F18 positron emission tomography (PET) in nondemented oldest-old. Methods: Thirteen nondemented (normal or cognitively impaired nondemented) participants (median age, 94.2 years) from The 90+ Study underwent florbetapir-PET scanning within 3 months of baseline neuropsychological testing. Amyloid load was measured with a semi-automated quantitative analysis of average cortical-to-cerebellar standardized uptake value ratio (SUVr) and a visual interpretation (A beta- or A beta+). Neuropsychological testing was repeated every 6 months. Results: At baseline, SUVr correlated significantly with tests of global cognition and memory. During follow-up (median, 1.5 years), the A beta+ group had steeper declines on most cognitive tests, particularly global cognitive measures. Conclusion: This preliminary study suggests that greater amyloid load is associated with poorer cognition and faster cognitive decline in nondemented oldest-old. Amyloid load may identify individuals at increased risk of developing Alzheimer's disease. (C) 2013 The Alzheimer's Association. All rights reserved.