Apr 22, 2014


Interviewer: A blood test to detect Alzheimer's? We'll talk about that next on The Scope.

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Interviewer: A simple blood test that could detect Alzheimer's has been found. We're going to get some perspective on that now on The Scope from Dr. Norman Foster. He's the Director of the Center for Alzheimer's Care Imaging and Research at the University of Utah. They are calling this a landmark discovery, but I want some perspective on it. Is it really that much of a landmark? How soon might we see this type of a test? Is it something to get excited about? Can you give me some insight?

Dr. Norman Foster: Well this is a very selective and specialized kind of test, and that's what makes it exciting to researchers like me. The test was developed on the basis of an epidemiologic study in which they took individuals who were cognitively normal, took a blood sample, and then found out what changes in the blood they had after two years of follow-up. And so some of those normal individuals continued to be normal and others developed cognitive problems and some even Alzheimer's disease.

Interviewer: Okay.

Dr. Norman Foster: And so it's kind of a retrospective study. It doesn't identify Alzheimer's disease itself. It's really a predictive test; that is, is there a blood test that we can give to patients who are normal individuals for that matter, and know who is going to develop cognitive problems in the next two to three years. That's what this test does.

Interviewer: And from what I understand they took the blood samples of the regular healthy people. A few years later some of those developed some of these cognitive issues. They took blood again and then they found that there were ten or so lipids, or fats, that were similar in the people that developed the cognitive disabilities. Am I summarizing that correctly?

Dr. Norman Foster: That's right; there were these ten lipids that were found and they were found only in those people who two years later had developed these cognitive problems.

Interviewer: So is there any sort of hesitation you have as a researcher on this particular research, or is this something truly to be excited about?

Dr. Norman Foster: Well this is a surprising result. First, we had ahead of time no reason to suspect that this particular panel of lipids would reflect what brain function would be like later.

Interviewer: Okay.

Dr. Norman Foster: This is blood and not in the brain, so it is somewhat remote from the brain. There's a blood/brain barrier so that there's a distinction between what is found in the brain usually and what's in the blood.

Interviewer: Okay.

Dr. Norman Foster: So having a blood test is surprising, and that it reflects brain function or future brain function in this case is surprising. I think the point here is not just that it predicted that cognitively normal elderly people would develop memory problems, but when that would happen.

Interviewer: Is this a direct causation or is this an association or how would you best define that?

Dr. Norman Foster: It's definitely as association only.

Interviewer: Okay.

Dr. Norman Foster: Most of the tests that we have, a diagnostic test for Alzheimer's disease that we might talk about, for example, usually are reflecting the changes in the brain of Alzheimer's disease. This isn't necessarily linked to that at all. This is not a diagnostic test for Alzheimer's disease; it's a predictive test in the blood, and that's an important difference. We wouldn't necessarily expect that these same lipids would be present in people who already have dementia, for example, or already have Alzheimer's disease. And in fact if what I'm speculating is right, this really represents a change in the brain function, then it might go away or might not be found in people who are clearly impaired already.

Interviewer: As far as tests go they claimed, the researchers, that this is 90% accurate. That seems pretty accurate. Is my definition of accurate the same as yours?

Dr. Norman Foster: Well in order for it to be clinically useful it has to be very accurate. We don't want to be telling people that within two years you're going to have Alzheimer's disease and be wrong.

Interviewer: Yeah.

Dr. Norman Foster: So 90% sounds high, but it may need to even be higher than that to be sure, because we can't afford to tell five out of a hundred people that they're going to develop Alzheimer's disease and then have that not happen.

Interviewer: Is there any way to predict how much more time would have to pass? Let's pretend that they are onto something, that this causation is accurate, this indicator is accurate five years until a doctor would be able to have a test that they could be able to administer; ten years, or is there no way to tell?

Dr. Norman Foster: It may be difficult for another laboratory to replicate the exact panel that this laboratory did, with the same sensitivity and specificity. So there may be some...

Interviewer: So even the process is something else...

Dr. Norman Foster: The process, the validation could be a little difficult to do.

Interviewer: This might seem off on a tangent, and if it is please pull me back in, but is there any potential that these ten lipids could have any significance to insight to future cures?

Dr. Norman Foster: Well I think understanding why this panel showed up in this large screen, essentially they tested a lot of things and they identified these ten as being important. So they picked from a big variety of tests these ten and that seemed to work best. Why is it ten? Why not 15 or 5? And so those are the kinds of things that really make you wait for validation to be very confident about the finding.

Interviewer: Is there a takeaway message for our listeners?

Dr. Norman Foster: The issue here is what about this kind of test? We haven't had such a test available before, and so the question is how would we use it? Should we use it? If there is a blood test that will tell me whether or not in the next two years I become impaired would I take that test. And if so, even without a cure for Alzheimer's disease how would that change my life; and in fact we are beginning now to consider and we are beginning clinical trials of drugs we think may prevent the development or slow the development, delay the development of Alzheimer's disease and we're not quite sure how patients and families will think about that. If you don't have any symptoms now, then would you be willing to take a strong potentially expensive drug with side effects to decrease your risk of Alzheimer's disease in the future?
One of the exciting facets of this study is it really pushes us to think about these problems. We now have other tests that can find Alzheimer's disease pathology in people who don't have symptoms. But we don't know how to use those tests very well, or how patients and families, actually not just patients, but people in the community, because that's who we would be approaching, to consider these prevention trials.

Interviewer: So it's a brave new world it sounds like.

Dr. Norman Foster: It is; it's a brave new world and it has many opportunities, but we have to be careful going forward because of ethical considerations, and also because this is untested water and there still remains a high degree of stigma related to Alzheimer's disease and memory problems. And now that we're beginning to be able to think about Alzheimer's disease before even memory problems develop, then we're going to have to think again about how we react to the Alzheimer's disease and how we are able to respond, not just to people how have symptoms or have dementia, but also people who may be at risk. So we need to maintain respect and dignity, not just for people who have Alzheimer's disease and other forms of dementia, but people who are also at high risk.

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