Scientists are reporting a significant step toward developing a blood test for Alzheimer's – identifying a group of biomarkers that correlated with the development of the disease in three independent groups of patients.
The findings, reported by Emory University School of Medicine researchers in the journal Neurology, indicate an inexpensive, convenient test for Alzheimer's disease may be within reach.
"Reliability and failure to replicate initial results have been the biggest challenge in this field," said lead researcher Dr. William Hu, assistant professor of neurology at Emory. "We demonstrate here that it is possible to show consistent findings."
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For the new study, Hu and his collaborators at the University of Pennsylvania and Washington University, St. Louis, measured the levels of 190 proteins in the blood of 600 healthy volunteers and people who had been diagnosed with Alzheimer's disease or mild cognitive impairment.
They found levels of 17 of those proteins were significantly different in people with Alzheimer's and cognitive impairment. Changes in blood levels of four of them – apolipoprotein E, B-type natriuretic peptide, C-reactive protein and pancreatic polypeptide – strongly correlated with other research involving Alzheimer’s patients that found they may cause changes in the brain connected with Alzheimer's.
"Though a blood test to identify underlying Alzheimer's disease is not quite ready for prime time given today's technology, we now have identified ways to make sure that a test will be reliable," said Hu. "In the meantime, the combination of a clinical exam and [spinal tap] remains the best tool for diagnosis in someone with mild memory or cognitive troubles."
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Neurologists currently diagnose Alzheimer's disease based mainly on clinical symptoms. Additional information can come from PET brain imaging, which tends to be expensive, or analysis of a spinal tap, which can be painful.
The study was funded, in part, by the National Institutes of Health.