THE ROLE OF β-AMYLOID IN SUPERAGERS WITH SUPERIOR MEMORY PERFORMANCE AND PRESERVED BRAIN MORPHOMETRY

Abstract

Previous studies have shown that SuperAgers avoid normal age-related cortical thinning in key regions, supporting their superior memory performance (Harrison et al., 2012; Sun et al., 2016). It is not known whether SuperAgers similarly avoid β-amyloid accumulation, a process also associated with advancing age. We examined 150 participants enrolled in the Berkeley Aging Cohort Study who were aged 70 or older, had structural MRI and PiB-PET scan data quantifying β-amyloid in the brain. Of these, 26 met criteria for a SuperAger (SA): a score of 14 or above on CVLT long delay free recall (LDFR) and normal for age performance on Trails B (Delis et al., 2000; Tombaugh et al., 2004). 76 participants met criteria for typical older adults (TOA). We compared cortical thickness and hippocampal volume in SA to TOA. We calculated a global PiB-PET distribution volume ratio (DVR) and compared the relationship between age and global PiB in SA and TOA. Multiple regression models were used to determine relationships between morphometric measures, global PiB, memory and processing speed. Cortical thickness analyses revealed several regions of preserved cortical integrity in SA compared to TOA (p<0.05, uncorrected), including right anterior cingulate and prefrontal cortex, which have been previously associated with SA. Hippocampal volumes were greater in SA compared to TOA (p=0.03). Hippocampal volume, controlling for head size and age, was positively correlated with CVLT LDFR across both groups (r=0.32, p=0.001). There was a negative correlation between age and PiB in SA (r=-0.42, p=0.035) that was not observed in TOA (r=0.10, p=0.39), such that only the younger SA participants had high global PiB burden.