Over time, blood tests could be used earlier, allowing people who were starting to have mild memory problems to know if they would develop Alzheimer’s or if they had another condition that could be less aggressive or quicker, Dr. Weiner said.
And, Dr. Tanzi said, blood tests could be performed on people without hindrance in the future, perhaps as initial screening tools that will be followed by PET scans if troubling levels of biomarkers are detected.
“It has the promise of making early detection of the disease possible before we have symptoms,” said Dr. Tanzi, something the field would only recommend for clinical use if there were effective ways to prevent or treat Alzheimer’s.
Dr. Hansson said his laboratory was studying whether the test could predict dementia in people without disabilities or in those with mild memory problems.
The test in the JAMA study used a method called an immunoassay to detect compounds that bind to antibodies. Several of these trials are underway. The particular trial in the study was developed by Eli Lilly and Company, which provided materials and three employees to conduct the trials; The authors reported that the company was allowed to review the manuscript but not veto anything in it. Most of the funding for the study came from government agencies and foundations in Sweden and the United States.
At the Alzheimer’s Association conference, Dr. Hansson and a co-author, Dr. Kaj Blennow, presented their findings, as did two other research teams working on tau blood tests.
A test, developed by a team at the University of Washington at St. Louis that included Dr. Randall Bateman, Dr. Suzanne Schindler, and Nicolas Barthélemy, used a method called mass spectrometry, which detects entire molecules of tau or amyloid. In a study published Tuesday in the Journal of Experimental Medicine, that team found that the same form of tau in the JAMA study, p-tau217, correlated more closely with amyloid accumulation in the brain than another form, p-tau. 181, which some researchers have focused on, Dr. Schindler, an assistant professor of neurology, said it could be because p-tau217 emerges earlier in the Alzheimer’s disease process.