Furthermore, beyond the fact that most experts said they do not believe a blood test will ever surpass the accuracy of the current neuropsychological test, many experts don't believe that ABeta42 is the protein we should be focusing on as a biomarker for the disease.
"ABeta42 is not specific to Alzheimer's disease and not highly correlated with cognition," Royall said.
In fact, most researchers are holding out hope for another diagnostic tool, altogether: amyloid imaging. An amyloid imaging agent would allow doctors to directly examine the clumps and tangles of this protein in the brain -- a protein that many believe is directly linked to Alzheimer's.
But, with so many exciting new tools for diagnosing Alzheimer's disease still in the pipeline, experts note that, as of yet, there are no diagnostic tools for the disease that are ready for clinical application.
"This is pure research," said Dr. John Messmer, associate professor of family and community medicine at the Penn State College of Medicine. "It is not a final application of a diagnostic test.
"It's just one more incremental step toward understanding the disease."