JEFFREY BROWN: And finally tonight: the possibilities of earlier testing for Alzheimer's disease.
Margaret Warner has the story.
MARGARET WARNER: More than five million Americans suffer from the debilitating effects of Alzheimer's disease. Currently, doctors diagnose the degenerative brain disease by tracking the progression of dementia or memory loss, as revealed by the patient's behavior and the results of cognitive tests.
But, this week, for the first time in 25 years, medical experts proposed revamping the diagnostic tools and categories to detect Alzheimer's at its earliest stages, when there are few, if any, symptoms.
The new diagnostic tools, which were presented at the Alzheimer's Association meeting in Honolulu this week, would include so-called biomarker tests, including brain imaging methods like MRIs and PET scans, as well as spinal fluid tests to detect changes in the brain.
Using the information from the new tests, researchers are also proposing new criteria that would diagnose Alzheimer's in three stages: a new category called pre-clinical, before any symptoms appear; the second stage of mild cognitive impairment; and, lastly, the most advanced form of the disease, Alzheimer's dementia.
Researchers believe these new guidelines and tests could help detect the disease as it's developing in a patient, a decade before obvious symptoms appear. And that, they say, could double or triple the number of Americans diagnosed with Alzheimer's.
For the latest on these Alzheimer's developments, we turn to Creighton Phelps, director of the Alzheimer's Disease Center's program at the National Institute on Aging. It helped put together the expert panels that are recommending these changes.
And, Creighton Phelps, welcome.
What is driving these proposed changes now to both the testing and the categories of Alzheimer's?
CREIGHTON PHELPS, National Institute on Aging: The science has really grown immensely since 1984, when these original guidelines were first written.
And so we wanted to update them and to include signs that relates to the underlying biology of Alzheimer's disease and how that manifests itself in clinical symptoms, and see if we can link that up a little tighter than it's been done before.
MARGARET WARNER: So, what do these tests, say, the different brain scans or the spinal taps, what can it tell you about the brain, relevant to Alzheimer's, that you couldn't tell, say, 10 or 15 years ago?
CREIGHTON PHELPS: We now have imaging techniques, such as something called Pittsburgh Compound B, which allows us to see amyloid protein that occurs in the brains of Alzheimer's patients.
What we're -- we were a bit surprised to find out is that when we started imaging people who haven't been diagnosed with Alzheimer's, we were seeing some changes in the brain that related to the Alzheimer's changes, like the deposition of the amyloid protein.
MARGARET WARNER: Where are we now product, broadly speaking, in our understanding of Alzheimer's, both the causes and the progression? And how would this help advance that?
CREIGHTON PHELPS: Risk factors such as genetic risk factors will help us find groups of people that may be at higher risk. And we would monitor them to see if these changes develop until the time they get Alzheimer's disease. And, once again, this is a research project, and won't be applied clinically widespread -- in a widespread way -- until after this has been validated.
But if we can link that up to the risk factors and the final appearance of the disease by using these biomarkers, it will be a big step forward.
MARGARET WARNER: Now, currently, there are no drugs on the market at all that actually affect the rate of progression of the disease, are there?
CREIGHTON PHELPS: No, but there are many ideas and some drugs under development in clinical trials that are doing just that, looking at the biology of the disease, finding points where interventions could be placed to see if we could stop it or to at least slow it down.
MARGARET WARNER: So, for an individual patient, what would be the advantage -- I mean, until there is some kind of drug that actually does -- does some help, what would be the advantage of knowing early?
CREIGHTON PHELPS: Yes, that's controversial, yet there is some advantages, because it allows patients and families to plan.
If you know for sure you're going to get the disease, then you will start doing things a little differently, perhaps, than you would have otherwise, putting your affairs in order, getting powers of attorney arranged, so that, when you are no longer competent, someone else can help take care of you, both in the legal and financial and -- and also health care.
MARGARET WARNER: Is it fair to say there are downsides?
CREIGHTON PHELPS: Well, the downsides are that it's a difficult thing to deal with for some people. And there are those who don't want to hear this.
And, also, the downsides of knowing this earlier is probably going to put some -- some pressure on the health care system to take care of more people, because more people will be identified than were in the past.
MARGARET WARNER: So, is one of the objectives here, though, that you are going to generate a larger pool of people at an earlier stage who are at least available to take part in the clinical trials, in other words, that you will be able to test these drugs at an earlier stage of the disease?
CREIGHTON PHELPS: Yes, that's exactly what we hope to do.
MARGARET WARNER: You want to expand on that just a little bit?
CREIGHTON PHELPS: What we are hoping to do is to validate, with these biomarkers, the fact that symptoms are showing. And, in turn, we will look at the imaging. And that adds to our certainty of what's going on and that they are on their course to Alzheimer's.
It's those kinds of patients that we would want to choose for interventions, so that we -- because we are learning the natural history of the disease, we would then like to intervene as quickly as possible when we recognize what that is.
MARGARET WARNER: Mr. Phelps, thanks so much.
CREIGHTON PHELPS: My pleasure.