The Role of Amyloid PET in the Management of Alzheimer's Disease

In a study presented at the American Academy of Neurology annual meeting, researchers evaluated the role of amyloid-beta PET scans as a diagnostic tool in clinical settings, and their influence on management with respect to Alzheimer's disease therapies.

In this exclusive MedPage Today video, Christian Camargo, MD, of the University of Miami Miller School of Medicine, discusses the Khatib study.

Following is a transcript of his remarks:

Essentially, right now we're at a current place where diagnosing Alzheimer's disease, and by diagnosing I mean confirming the diagnosis by testing for the actual cause of Alzheimer's disease, the initiating of the first domino to fall, which is that protein that many of us have heard of, amyloid-beta. And in order to do so, there's different ways to do that. Right now some people have heard of the spinal tap, the cerebrospinal fluid test. There's even blood tests that can somewhat do it. But of course there's pitfalls in terms of accuracy and the invasiveness.

But what we did in our study was replicate what has been done at a larger scale by Gil Rabinovici, MD, at University of California San Francisco, which is in his case the IDEAS study. And what we've done is replicate that in two real-world community-based cohorts.

And essentially we're using philanthropic funds to give away free amyloid PET scans to see whether or not by using these tests to tell individuals whether or not they have the amyloid protein, ergo the Alzheimer's condition, that would help with the diagnostic accuracy and also with a specific management and choice of the use of Alzheimer's-specific drugs by the physicians in their memory clinics at the two respective clinical sites.

And lo and behold, it did actually. In fact, what we found is that all the physicians changed their diagnoses to reflect the 2018 National Institute on Aging/Alzheimer's Association guidelines, which are entirely based off the biomarker status. So, in other words, all the physicians agreed that if you have the amyloid positivity on the scan, that you have Alzheimer's. And if you don't have it, you don't have Alzheimer's.

And here's the big result that was very interesting. Even if the patients did not have Alzheimer's disease by that definition, so even if they were amyloid-negative, over half would still remain after discussing it with their physicians on some kind of Alzheimer's medication. So that's not to say that necessarily they're ignoring the diagnosis, but it is to say that after discussion with their physicians, they must have felt that there was still some benefit to be gained.

And there's lots of basis for that. There's some clinical studies that show perhaps there's some benefit in other kinds of dementias even if they're not based in Alzheimer's disease, such as Lewy body disease, such as vascular dementia, so forth. But of course, the converse was also very true that once individuals were confirmed to be positive, 91% were put on Alzheimer's drugs, whether it be the cholinesterase inhibitors like donepezil [Aricept], or memantine [Namenda].

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