Blood Test Helps Detect or Exclude Alzheimer's Disease

A blood test, which identifies biomarkers in blood serum may help clinicians accurately classify individuals with Alzheimer's disease (AD) as well as identifying people who do not have the disease.

A biomarker score has been devised using statistical analyses, which included levels of 24 protein biomarkers including the clotting protein fibrinogen, the anti-inflammatory cytokine interleukin-10 (IL-10) and the inflammatory marker, C-reactive protein.

In longitudinal case-control study carried at the Texas Tech University Health Sciences Center, Lubbock, TX, USA), 400 participants, 197 subjects with AD and 203 controls were enrolled. Nonfasting blood samples were collected in serum-separating tubes during clinical evaluations and multiple proteins were quantified though multiplex fluorescent immunoassay using colored microspheres with protein-specific antibodies.

Results from the multivariate logistic regression model demonstrate that the biomarker risk score was a significant, independent predictor of case status. Significant analysis of microarray analysis identified 14 differentially overexpressed or 9 underexpressed proteins in patients with AD relative to controls. Fibrinogen, IL-10 and C-reactive protein levels were amongst the inflammatory-related biomarkers that were underexpressed in AD patients.

The final biomarker risk score identified 80% of the Alzheimer's patients accurately, and correctly excluded 91% of those without AD. When age, sex, education, and whether the person had the apolipoprotein E (APOE) gene (linked to Alzheimer's disease) were taken into account, the score accurately identified 94% of the people with AD, and correctly classified 84% of those without. The study was published in the September 2010 issue of Archives of Neurology.

Sid E. O'Bryant, Ph.D., the lead author on the study concluded," In addition to offering more accessible, rapid and cost- and time-effective methods for assessment, biomarkers (or panels of biomarkers) also hold great potential for the identification of endophenotypes within AD populations that are associated with particular disease mechanisms." There are estimated to be between 2.4 million and 4.5 million Americans who have AD and there are approximately 417,000 people in the UK with the disease.

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