An Alzheimer's Fingerprint?

Had these proteins been identified before as potentially useful in diagnosing Alzheimer's?

Some of these proteins had been reported to relate to Alzheimer's in past studies, and others had not. However, none had stood out on their own as a diagnostic. It was only when considered together as a group that their power to identify Alzheimer's patients became evident.

What about the usual suspects— like A-beta 42 [the most toxic form of A-beta] and tau [a marker of neuronal death]? Did those turn up in your mix?

Those were not among the markers that came out in our study. I don't want to suggest they're not valid [targets for testing]. But because of the nature of our technology, they didn't fall into this pattern. In an ideal world, you might want to include those, but in a sense, you don't need them as long as you can get a characteristic group of proteins that will reliably show who has the disease and who doesn't.

How reliable was the test?

We actually report on two studies in this paper. In the first one, we had an initial group of 34 patients and 34 age-matched controls with other forms of dementia. The importance of this first group was to determine what the markers are. Autopsy studies showed the test was 94 percent [accurate]. We then performed a small validation study in a second group of patients with probable Alzheimer's to see if the results held.