It would seem difficult to put up worse numbers than experimental Alzheimer’s drugs, 99 percent of which have failed in clinical trials since 2002. But another corner of Alzheimer’s research has managed it: blood tests to either diagnose the disease in asymptomatic patients or predict which healthy people will develop it years in the future. Although you wouldn’t know it from frequent headlines proclaiming, “Blood test can predict Alzheimer’s,” the percentage of tests that looked promising in a (usually small) study but eventually fell flat is … 100 percent.
Despite the two dozen such failures, scientists aren’t giving up. On Wednesday, researchers in Europe and Australia reported in the journal Science Advances that blood levels of 10 proteins did a pretty good job of identifying which cognitively unimpaired people had high enough brain levels of beta-amyloid, a marker of the disease, to be classified as having preclinical (meaning, without symptoms) Alzheimer’s. The test isn’t accurate enough to make diagnoses as part of medical care, its creators say, but if it’s validated in additional studies, it could give drug companies a desperately needed tool: a cheap, easy way to identify preclinical Alzheimer’s.