In a study to be published later this month in the journal Neurology, scientists have taken a step toward developing a blood test for Alzheimer's disease (AD), finding a group of markers that hold up in statistical analyses in three independent groups of patients.
Researchers at the University of Pennsylvania and Washington University, St. Louis, measured the levels of 190 proteins in the blood of 600 study participants. The participants included healthy volunteers and those who had been diagnosed with AD or mild cognitive impairment (MCI), often considered a harbinger for Alzheimer's.
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 previously have been connected with AD. The analysis grouped together people with MCI and full Alzheimer's.
“We were looking for a sensitive signal,” says lead author William Hu, MD, PhD, assistant professor of neurology at Emory University School of Medicine. “MCI has been hypothesized to be an early phase of AD, and sensitive markers that capture the physiological changes in both MCI and AD would be most helpful clinically.” Hu adds, “The specificity of this panel still needs to be determined.”
