Association of Plasma β-Amyloid Level and Cognitive Reserve With Subsequent Cognitive Decline

Abstract

An estimated 36 million people currently have dementia, with the prevalence expected to double every 20 years.¹ Thus, biomarkers to identify elderly persons at risk of developing dementia could be useful for early prevention, if and when such interventions are available, and treatment. Plasma β-amyloid measurement has emerged as a promising biomarker, with lower β-amyloid 42 and 42/40 levels shown to be associated with increased risk of developing Alzheimer disease (AD).^2-4 However, both cross-sectional and prospective studies have reported conflicting results^5-7 that may be due to variations in participant diversity, follow-up time, and choice of laboratory assays.^2,3,5,6 In addition, few studies have investigated the association of plasma β-amyloid level and rate of cognitive decline as opposed to dementia. Thus, one objective of our study was to prospectively investigate the association between plasma β-amyloid 42 and 42/40 levels and cognitive decline over 9 years in a large cohort of biracial, community-dwelling older adults without dementia.