'5 Years Ago, I Would Have Told You It Was Science Fiction'

It could be the Holy Grail Alzheimer's researchers have been looking for: "This blood test very, very accurately predicts who’s got Alzheimer’s disease in their brain, including people who seem to be normal." That's how an Alzheimer's disease researcher not involved with a new study summed up that study's findings, which were published Tuesday in JAMA. As the New York Times explains, the blood test was almost as accurate as the current most accurate method of diagnosis: an autopsy after death. The study involved 1,402 people in Arizona, Sweden, and Colombia and measured a type of tau protein called p-tau217, per the AP. The test managed to establish whether patients who had dementia were suffering from Alzheimer's with 96% accuracy, and was also effective when tested on the largest group of relatives known to have genetic early-onset Alzheimer’s.

They live in Colombia, and 600 family members (about 10% of the extended family's total) were tested. Dementia symptoms typically set in midway through their 40s for those who develop Alzheimer's and the test managed to identify those who did and did not have the mutation at age 25. The Arizona component of the test compared the brain autopsies of 81 people with testing on blood that was taken before their death to establish accuracy. As for timing, we could potentially be as little as 2 or 3 years away from the rollout of such a test, following more clinical trials on more diverse populations and a review by federal regulators. Dr. Maria Carrillo, chief science officer at the Alzheimer’s Association, sounds bowled over: "I mean, really, five years ago, I would have told you it was science fiction.” (More Alzheimer's disease stories.)