Basically, they measured the levels of 190 proteins in the blood of 600 participants. The subjects studied included healthy volunteers and individuals that had been diagnosed with Alzheimer's disease or mild cognitive impairment (MCI).
“A subset of the 190 protein levels (17) were 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.”Coincidentally, they discovered a correlation among patients that showed changes in their levels of these four proteins and their measurements of proteins [beta-amyloid] levels in their cerebrospinal fluid, a protein previously connected with Alzheimer's disease. These correlations allowed researchers to group together people with MCI that may be at high risk of developing Alzheimer's.
"We were looking for a sensitive signal," says Hu. "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."
"The specificity of this panel still needs to be determined, since only a small number of patients with non-AD dementias were included," Hu says. "In addition, the differing proportions of patients with MCI in each group make it more difficult to identify MCI- or AD-specific changes."Unfortunately, researchers have not yet been able to uncover a simple blood test to detect Alzheimer’s disease; however they have discovered ways to ensure that any future tests will be reliable.
Therefore, neurologists will have to continue to diagnose Alzheimer's disease based mainly from an analysis of clinical symptoms or at times expensive PET brain imaging or painful spinal tap.
Blood Test for Alzheimer's Gaining Ground