Blood tests could eventually be used earlier, allowing people who were beginning to have mild memory issues to learn whether they would develop Alzheimer’s or instead had another condition that might be less aggressive or fast-moving, Dr. Weiner said.
And, Dr. Tanzi said, in the future blood tests might be given to people without any impairment, perhaps as initial screening tools to be followed with PET scans if worrisome levels of biomarkers were detected.
“It has the promise to make early detection of the disease possible, before we have symptoms,” Dr. Tanzi said, something the field would only recommend for clinical use if there were effective ways to prevent or treat Alzheimer’s.
Dr. Hansson said his lab was studying whether the test could predict dementia in people with no impairments or 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 such assays are being developed. The particular assay in the study was developed by Eli Lilly and Company, which provided materials and three employees to conduct the assays; the company was allowed to review the manuscript but not veto anything in it, the authors reported. 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.
One test, developed by a team at Washington University in 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 on 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 to amyloid buildup in the brain than another form, p-tau 181, that some researchers have been focusing on. Dr. Schindler, an assistant professor of neurology, said that might be because p-tau217 emerges earlier in the Alzheimer’s disease process.