An experimental blood test was highly accurate at distinguishing people with Alzheimer’s disease from those without it in several studies, boosting hopes that there soon may be a simple way to help diagnose this most common form of dementia.

Developing such a test has been a long-sought goal, and scientists warn that the new approach still needs more validation and is not yet ready for wide use.

But Tuesday’s results suggest they’re on the right track. The testing identified people with Alzheimer’s vs. no dementia or other types of it with accuracy ranging from 89% to 98%.

Results were discussed at the Alzheimer’s Association International Conference and some results were also were published in the Journal of the American Medical Association.

Last year, scientists reported encouraging results from experimental blood tests that measure abnormal versions of amyloid, one of two proteins that build up and damage Alzheimer’s patients’ brains. The new work focuses on the other protein — tau — and finds that one form of it called p-tau217 is a more reliable indicator. 

Dr. Oskar Hansson of Lund University in Sweden led a study of Eli Lilly’s test on more than 1,400 people already enrolled in dementia studies in Sweden, Arizona and Colombia. They included people with no impairment, mild impairment, Alzheimer’s and other neurological diseases.

The p-tau217 test outperformed a host of other measures for indicating which patients had Alzheimer’s as verified by brain scans. It also was comparable to the brain scans and some spinal tests in accuracy. According to the research, the test also identified signs of degenerative aging up to 20 years before symptoms and cognitive impairment. Researchers say a test could be ready for clinical use in about two to three years. 

With files from the Associated Press

Guest:

Eric M. Reiman M.D., executive director of Banner Alzheimer's Institute in Phoenix, Arizona and senior author on the study