An Alzheimer's Fingerprint?

But the validation test had a somewhat lower accuracy rate.

These were living patients, so we couldn't compare against autopsy results. Even in expert hands, clinicians only identify about 90 percent of cases correctly. [The lower accuracy rate] is not necessarily a weakness in our test, but could be a limitation in clinical diagnosis.

But you're still quite a long way from having a commercial test, aren't you?

I would estimate that it will be at least three to five years before a commercial test is available. I base that on the length of time it will take to carry out larger validation studies and to put the test into a form in which it is practical for commercial or clinical use. Right now, it is a laborious process to detect these markers. But the technology exists to measure them in other ways.

The major drawback I see here is that you have to put people through a spinal tap to do this test.

That is a drawback, I agree. It would certainly be wonderful to have a noninvasive test or a less invasive test, such as a blood test. But as a matter of practical consideration, spinal fluid is the only bodily component we can assess that's in direct contact with the brain. Blood is one or two steps removed, and it contains a more complex mix of proteins influenced by functions of all organs of the body. That's not an insoluble problem, but it does make it harder.