Associations of amyloid biomarkers with brain and cognitive changes from imaging, spinal fluid, and plasma

BACKGROUND: Positron emission tomography (PET), cerebrospinal fluid (CSF), and plasma assessments are used to measure amyloid abnormality in Alzheimer's disease (AD). However, it remains unclear if these three measures are similarly associated with brain structure and cognitive measures. METHODS: Linear regressions examined the relationship between amyloid levels measured by PET, CSF, and plasma and brain volumes, white matter hyperintensities (WMHs), and cognitive measures. RESULTS: Moderate correlations were found between PET and CSF amyloid measurements and PET and plasma measurements, while weak correlations were found between CSF and plasma. PET, CSF, and plasma amyloid measurements differed in their associations with brain volume, WMHs, and cognition. DISCUSSION: Using different measurement methods, amyloid was not consistently associated with volumetric or cognitive measures. Our findings also suggest that plasma markers may not be associated with cognitive and brain changes in the same manner as CSF and PET.