High serum Aβ and vascular risk factors in first-degree relatives of alzheimer's disease patients

Abstract

The main objective of this study was to determine whether elevated blood β-amyloid (Aβ) levels among the first-degree relatives of patients with Alzheimer's Disease (AD) are associated with vascular risk factors of AD. Serum Aβ was measured in samples from 197 cognitively normal first-degree relatives of patients with AD-like dementia. Study participants were recruited as part of an ancillary study of the Alzheimer's Disease Anti-inflammatory Prevention Trial (ADAPT subpopulation). The ADAPT subpopulation was found to be similar in age, sex, and ethnicity to another cognitively normal cohort (n = 98). Using cross-sectional analyses, we examined the association of Aβ with blood pressure, lipid levels, apolipoprotein E genotypes, and the use of prescribed medication to treat vascular risk factors in the ADAPT subpopulation. Aβ 1-40 was positively associated with age, use of antihypertensives, and serum creatinine, and we observed a marginal negative interaction on Aβ 1-40 associated with systolic blood pressure and use of antihypertensives. Serum Aβp 1-42 was associated with statin use and a positive correlation of Aβ 1-42 with HDL was observed among statin nonusers. These findings suggest that high Aβ in the periphery among the family history-enriched cohorts may be due to enrichment of vascular risk factors and may reflect presymptomatic AD pathology. It remains to be determined whether the association of Aβ with medications used for treating vascular risk factors indicates prevention of AD. Longitudinal evaluation of blood Aβ in this cohort will provide a better understanding of the significance of this association in AD etiology. © 2009 The Feinstein Institute for Medical Research.