Simple Blood Test Can Predict Dementia Risk

A new biomarker has been identified that can predict the risk of developing dementia by way of a simple blood test which in the long term could mean better prevention and at least postponement of the illness and at best evading the development all together.

The apolipoprotein E (APOE) ε4 allele is a major genetic risk factor for Alzheimer disease and dementia; however, it remains unclear whether plasma levels of apoE confer additional risk. Prevalence increases in step with aging, and as people's life years are continually on the rise in most countries, there is also an increasing need to be able to identify the citizens who are at the greatest risk of suffering dementia.

Scientists at the University of Copenhagen (Denmark) enrolled 75,708 participants from the general population; and tested whether low plasma levels of apoE at study enrollment were associated with increased risk of future Alzheimer disease and all dementia, and whether this association was independent of ε2/ε3/ε4 APOE genotype.

Multifactorial adjusted hazard ratios (HRs) for Alzheimer disease and all dementia increased from the highest to the lowest apoE tertile. Multifactorial adjusted HRs for lowest versus highest tertile were 2.68 for Alzheimer disease and 1.80 for all dementia. After further adjustment for ε2/ε3/ε4 APOE genotype, plasma apoE tertiles remained associated with Alzheimer disease and all dementia. Plasma apoE tertiles did not interact with ε2/ε3/ε4 APOE genotype on risk of Alzheimer disease or all dementia. In a subanalysis, the -219G>T GT promoter genotype, associated with low plasma apoE levels, remained significantly associated with increased risk of Alzheimer disease after adjustment for ε2/ε3/ε4 APOE genotype.

The authors concluded that low plasma levels of apoE are associated with increased risk of future Alzheimer disease and all dementia in the general population, independent of ε2/ε3/ε4 APOE genotype. This is clinically relevant, because no plasma biomarkers are currently implemented. Hence, plasma levels of apoE may be a new, easily accessible preclinical biomarker. Ruth Frikke-Schmidt MD, PhD, the senior author of the study said, “The blood test will help provide a more precise risk evaluation of a citizen's risk of developing dementia later in life. Thus the citizens at the greatest risk of developing the illness are more easily identified than at present. The blood test will enable an earlier and more focused prevention effort, thus prolonging the onset of the illness and raising the individual's quality of life.” The study was published in the February 2015 issue of the journal Annals of Neurology.

Related Links:
University of Copenhagen