Scientists claim measuring the levels of just four blood proteins can diagnose Alzheimer’s disease and mild cognitive impairment (MCI), which is widely believed to represent a signal that Alzheimer’s disease is likely to develop.
William Hu, M.D., at Emory University School of Medicine, and colleages at the University of Pennsylvania and Washington University St. Louis, measured the levels of 190 proteins in the blood of 600 healthy volunteers, and patients diagnosed with Alzheimer’s disease and MCI. Their initial results found that 17 proteins were present at very different levels in the blood of the patients compared with the healthy individuals.
Then, when they looked more closely at these 17 proteins using data from another 566 people in the multicenter Alzheimer’s Disease Neuroimaging Initiative, they found that just four appeared to correlated with MCI and Alzheimer’s disease: apolipoprotein E (ApoE), B-type natriuretic peptide, C-reactive protein, and pancreatic polypeptide. Importantly, changes in blood levels of the four proteins also correlated with levels of β amyloid in cerebrospinal fluid.
The researchers admit that the sensitivity and specificity of their findings will need to be validated in far more patients, especially those with non-Alzheimer’s dementia, before a diagnostic blood test can be developed. Nevertheless, as Dr. Hu points out, “We were looking for a sensitive signal. MCI has been hypothesized to be an early phase of Alzheimer’s disease, and sensitive markers that capture the physiological changes in both MCI and Alzheimer’s disease would be most helpful clinically ... We demonstrate here that it is possible to show consistent findings ... 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.”
Drs. Hu, et al are describing their results in a forthcoming issue of Neurology, in a paper titled “Plasma multianalyte profiling in mild cognitive impairment and Alzheimer’s disease.”