A Blood Test Accurately Diagnosed Alzheimer's 90% of the Time, Study Finds

>It was not very accurate with the earliest stage, called subjective cognitive decline, when patients begin to perceive their memory to be failing. Dr. Hansson said that lower accuracy probably occurred because many people with subjective cognitive decline do not turn out to have Alzheimer’s.

That's an intriguing statistical statement to make. It implies that the test simply flags lots of positives, and the accuracy gets worse in populations where the number of true positives is low. That's not such a crime (especially due to the cost of false negatives), but I don't understand why it's framed so innocuously in this way.

It's also interesting that the article doesn't mention the false-positive/false-negative rates for the blood tests, just for the physicians' diagnoses. Is there some spin on the numbers that we're not meant to see?

Discussion from the CNN version of this article 17 hours ago: https://news.ycombinator.com/item?id=41094571