Plasma Amyloid-β Biomarker Associated with Cognitive Decline in Preclinical Alzheimer’s Disease

Abstract

Background: Using immunoprecipitation-mass spectrometry, we recently developed and validated a plasma composite biomarker for the assessment of amyloid-β (Aβ) levels. However, as yet, its relationship with clinical outcomes remains unclear. Objective: We aimed to examine the relationship between this plasma Aβ composite biomarker and cognitive function in cognitively normal older adults in two independent cohorts. Methods: Participants enrolled in the Australian Imaging, Biomarkers and Lifestyle (AIBL) study and the National Centre for Geriatrics and Gerontology (NCGG) study had undergone Aβ neuroimaging using positron emission tomography (PET), cognitive assessments and provided blood samples. We derived a high-performance plasma Aβ composite biomarker by immunoprecipitation with mass-spectrometry. Results: Both continuous and categorical measures of the plasma Aβ composite biomarker were significantly related to decline in episodic memory and executive function. The magnitude of effects of the plasma Aβ composite on episodic memory and executive function were comparable to that observed for the effects of PET Aβ levels on these same outcome measures. Conclusion: Several plasma Aβ biomarkers have been developed, but none have yet been applied to investigate their relationship with cognitive outcomes. Our results have important implications for the use of this biomarker in the detection of at-risk individuals.