Blood Test for Alzheimer's Holds Promise

The markers were statistically reliable in three independent groups of patients.

Scientists measured the levels of 190 proteins in the blood of 600 study participants at the University of Pennsylvania (Philadelphia, PA, USA) and Washington University, St. Louis (MO, USA). Study participants included healthy volunteers and those who had been diagnosed with Alzheimer's disease or mild cognitive impairment (MCI). MCI, often considered a harbinger for Alzheimer's disease, causes a slight but measurable decline in cognitive abilities.

A subset of the 190 protein levels (17) was significantly different in people with MCI or Alzheimer's. When those markers were checked against data from 566 people participating in the multicenter Alzheimer's disease neuroimaging initiative, only four markers remained: apolipoprotein E, B-type natriuretic peptide, C-reactive protein, and pancreatic polypeptide.

Changes in levels of these four proteins in blood also correlated with measurements from the same patients of the levels of proteins [beta-amyloid] in cerebrospinal fluid that were previously connected with Alzheimer's. The analysis grouped together people with MCI, who are at high risk of developing Alzheimer's, and full Alzheimer's.

"Reliability and failure to replicate initial results have been the biggest challenge in this field," said lead author William Hu, MD, PhD, assistant professor of neurology at Emory University School of Medicine (Atlanta, GA, USA). "We demonstrate here that it is possible to show consistent findings."

"The specificity of this panel still needs to be determined, since only a small number of patients with non-AD dementias were included," Prof. Hu said. "In addition, the differing proportions of patients with MCI in each group make it more difficult to identify MCI- or AD-specific changes."

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University of Pennsylvania
Washington University, St. Louis
Emory University School of Medicine