Alzheimers Dement. 2016 Jul;12(7):805-14.
INTRODUCTION: The current study investigated the relationship between beta-amyloid (Aβ) and cognition in a longitudinal cohort of late middle-aged participants enriched for Alzheimer’s disease (AD) risk due to parental history of the disease. METHODS: 184 participants (mean age=60; 72% with a parental history of AD) completed a [C-11]PiB positron emission tomography scan and serial cognitive evaluations. A global measure of Aβ burden was calculated, and composite scores assessing learning, delayed memory, and executive functioning were computed for each evaluation. RESULTS: Higher Aβ burden was associated with classification of psychometric mild cognitive impairment (MCI) at most recent cognitive evaluation (p < .01). Linear mixed-effects regression results indicated higher Aβ was associated with greater rates of decline in delayed memory (p < .01) and executive functioning (p < .05). APOE ε4 status moderated the relationship between Aβ and episodic memory trajectories (p’s < .01). DISCUSSION: In a sample at higher risk for AD, greater Aβ burden in late middle-age is associated with increased likelihood of MCI at follow-up and steeper rates of cognitive decline.