Beta-amyloid and cognitive decline in late middle age: Findings from the WRAP study

Clark, L. R., Racine, A. M., Koscik, R., Okonkwo, O. C., Engelman, C. D., Carlsson, C. M., Asthana, S., Bendlin, B. B., Chappell, R. J., Nicholas, C. R., Rowley, H. A., Oh, J., Hermann, B., Sager, M. A., Christian, B., & Johnson, S. C.

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.


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