No correlation between time-linked plasma and CSF A<tex>$\beta$</tex> levels
Faculty of Pharmaceutical, Biomedical and Veterinary Sciences . Biomedical Sciences
Neurochemistry international. - Oxford
, p. 820-825
University of Antwerp
Plasma â-amyloid protein (Aâ) isoforms are considered potential biomarkers for Alzheimer's disease (AD) and dementia. The relation between plasma and cerebrospinal fluid (CSF) levels of Aâ isoforms remains unclear. In order to identify possible correlations between Aâ levels in plasma and CSF we determined Aâ levels in time-linked plasma and CSF samples. Aâ concentrations in plasma (Aâ142 and AâN42) and CSF (Aâ142) samples from 49 AD patients, 47 non-Alzheimer's disease dementia (NONAD) patients, 39 MCI patients and 29 controls were determined using a multi-parameter fluorimetric bead-based immunoassay using xMAP® technology (for plasma) and a conventional single-parameter ELISA (for CSF). Plasma Aâ142 concentrations did not correlate with CSF Aâ142 concentrations in the total study population, or in the different diagnostic groups. No correlations between plasma AâN42 and CSF Aâ142 levels were found either. The CSF/serum albumin index did not show any significant differences between AD, NONAD, MCI and controls. These results suggest that the Aâ levels in plasma are independent of the Aâ levels in CSF both in dementia and controls. The fact that CSF and plasma Aâ do not correlate in patients as well as controls and no significant differences in plasma Aâ142 or AâN42 between patients and controls can be detected hampers the diagnostic utility of the plasma Aâ levels as biomarkers for dementia.