Serum albumin and beta-amyloid deposition in the human brain

Abstract

ObjectivesTo investigate the relationships of serum albumin with in vivo Alzheimer disease (AD) pathologies, including cerebral β-amyloid (Aβ) protein deposition, neurodegeneration of AD-signature regions, and cerebral white matter hyperintensities (WMH), in the human brain.MethodsA total of 396 older adults without dementia underwent comprehensive clinical assessments, measurement of serum albumin level, and multimodal brain imaging, including [11C] Pittsburgh compound B-PET,18F-fluorodeoxyglucose-PET, and MRI. Serum albumin was categorized as follows: <4.4 g/dL (low albumin), 4.4 to 4.5 g/dL (middle albumin), and >4.5 g/dL (high albumin; used as a reference category). Aβ positivity, AD-signature region cerebral glucose metabolism (AD-CM), AD-signature region cortical thickness (AD-CT), and WMH volume were used as outcome measures.ResultsSerum albumin level (as a continuous variable) was inversely associated with Aβ deposition and Aβ positivity. The low albumin group showed a significantly higher Aβ positivity rate compared to the high albumin group (odds ratio 3.40, 95% confidence interval 1.67–6.92,p= 0.001), while the middle albumin group showed no difference (odds ratio 1.74, 95% confidence interval 0.80–3.77,p= 0.162). Neither serum albumin level (as a continuous variable) nor albumin categories were related to AD-CM, AD-CT, or WMH volume.ConclusionsLow serum albumin may increase the risk of AD dementia by elevating amyloid accumulation. In terms of AD prevention, more attention needs to be paid to avoid a low serum albumin level, even within the clinical normal range, by clinicians.