Abstract | OBJECTIVES: METHODS: We determined the plasma A beta 1-40 and A beta 1-42 levels of 274 nondemented subjects (232 normals and 42 with MCI) in 1998-1999 and repeated the measurements in 2002-2003. The mean age of the subjects at baseline was 79.3 +/- 3.6 years. We examined the association between A beta levels and incident AD over the ensuing 4.5 years, controlling for age, cystatin C level (marker of glomerular function), apolipoprotein E-4 allele, Modified-Mini-Mental State Examination scores, and MRI-identified infarcts. RESULTS: In an unadjusted prospective model in normal subjects, both A beta 1-40 and A beta 1-42 levels in 1998-1999 were associated with incident AD (n = 55) in 2002-2003 (longitudinal analysis). In the fully adjusted multivariate model, neither A beta 1-42 nor A beta 1-40 nor their ratio was associated with incident AD. However, adjustment had a very small effect on point estimates for A beta 1-42, from an odds ratio (OR) of 1.61 (p = 0.007) in the unadjusted model to an OR of 1.46 (p = 0.08) in the fully adjusted model. In 2002-2003 (cross-sectional analysis), only the unadjusted models showed that both peptides were associated with AD. CONCLUSIONS: Plasma A beta levels are affected by age and by systemic and CNS vascular risk factors. After controlling for these conditions, A beta-40 and A beta 1-42 are weak predictors of conversion to Alzheimer disease (AD) in normal subjects and are only weakly associated with AD in cross-sectional analysis. Consequently, plasma levels of A beta do not seem to be useful biomarkers for AD.
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Authors | O L Lopez, L H Kuller, P D Mehta, J T Becker, H M Gach, R A Sweet, Y F Chang, R Tracy, S T DeKosky |
Journal | Neurology
(Neurology)
Vol. 70
Issue 19
Pg. 1664-71
(May 06 2008)
ISSN: 1526-632X [Electronic] United States |
PMID | 18401021
(Publication Type: Journal Article, Research Support, N.I.H., Extramural)
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Chemical References |
- Amyloid beta-Peptides
- Apolipoprotein E4
- Biomarkers
- CST3 protein, human
- Cystatin C
- Cystatins
- Peptide Fragments
- amyloid beta-protein (1-40)
- amyloid beta-protein (1-42)
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Topics |
- Age Factors
- Aged
- Aged, 80 and over
- Alzheimer Disease
(blood, epidemiology, physiopathology)
- Amyloid beta-Peptides
(blood)
- Apolipoprotein E4
(genetics)
- Biomarkers
(analysis, blood)
- Brain
(metabolism, pathology, physiopathology)
- Cerebrovascular Disorders
(epidemiology)
- Comorbidity
- Cross-Sectional Studies
- Cystatin C
- Cystatins
(blood)
- Female
- Humans
- Incidence
- Longitudinal Studies
- Magnetic Resonance Imaging
- Male
- Models, Statistical
- Neuropsychological Tests
- Peptide Fragments
(blood)
- Predictive Value of Tests
- Prospective Studies
- Reference Values
- Risk Factors
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