ABSTRACT
OBJECTIVE: To determine whether a high prevalence (55%) of Aß deposition in a cohort of individuals remaining dementia-free into their 9th and 10th decades is associated with cognitive decline prior to imaging. METHODS: A total of 194 participants (mean age 85.5 years, range 82-95) who completed the Ginkgo Evaluation of Memory Study (GEMS) and remained dementia-free subsequently completed Pittsburgh compound B-PET imaging. We examined cross-sectional associations between Aß status and performance on a broad neuropsychological test battery completed at GEMS entry 7-9 years prior to neuroimaging. We also longitudinally examined cognition over annual evaluations using linear mixed models. RESULTS: At GEMS screening (2000-2002), participants who were Aß-positive in 2009 had lower performance on the Stroop test (p < 0.01) and Raven's Progressive Matrices (p = 0.05), with trend level difference for Block Design (p = 0.07). Longitudinal analyses showed significant slope differences for immediate and delayed recall of the Rey-Osterrieth figure, semantic fluency, and Trail-Making Test parts A and B, indicating greater performance decline prior to neuroimaging for Aß-positive relative to Aß-negative participants (ps < 0.05). CONCLUSIONS: Highly prevalent Aß deposition in oldest-older adults is associated with cognitive decline in visual memory, semantic fluency, and psychomotor speed beginning 7-9 years prior to neuroimaging. Mean differences in nonmemory domains, primarily executive functions, between Aß-status groups may be detectable 7-9 years before neuroimaging.
