[00:00.00]New blood tests could help to identify, or diagnose, Alzheimer's disease faster and with more accuracy, researchers reported recently.
[00:13.97]However, some of the tests for the brain-wasting disease appear to work better than others.
[00:23.11]Doctors can confirm Alzheimer's in a patient if they find one of the disease's main signs: the development, or buildup, of a sticky protein called beta-amyloid.
[00:39.34]Currently, doctors use brain imaging or a special test known as a spinal tap to look for beta-amyloid buildup.
[00:50.51]Brain imaging is hard to get and spinal taps are painful.
[00:55.75]Instead, many patients are diagnosed based on their behavior and cognitive exams.
[01:05.16]Now, labs have begun offering blood tests that can show some signs of Alzheimer's. Scientists are excited about the possibilities that the tests offer.
[01:20.32]But the tests are not widely used yet because there is little data to guide doctors about which kind to order and when.
[01:30.96]The U.S. Food and Drug Administration (FDA) has not officially approved any of them, and few patients have insurance coverage for such tests.
[01:46.80]"What tests can we trust?" asked Dr. Suzanne Schindler of Washington University in St. Louis. Schindler is part of a research project examining the tests.
[02:01.68]While some tests are very accurate, Schindler said, "other tests are not much better than a flip of a coin."
[02:12.15]More than 6 million people in the United States and millions more around the world have Alzheimer's, the most common form of dementia.
[02:24.15]Its usual signs, or "biomarkers," are amyloid plaques and abnormal tau protein that leads to tangles that damage neurons.
[02:37.13]New drugs such as Leqembi and Kisunla can slow the disease a little.
[02:44.05]The medicines remove amyloid from the brain.
[02:48.29]But these drugs only work in the early part, or stage, of Alzheimer's progression.
[02:55.81]Few patients get the costly brain scans and invasive spinal taps that could show early stage Alzheimer's.
[03:04.64]Even specialists struggle to tell if Alzheimer's or something else is to blame for a patient's problems.
[03:14.61]Schindler said she sometimes has patients "who I am convinced have Alzheimer's disease and I do testing and it's negative."
[03:24.59]A limited number of doctors have carried out blood tests for Alzheimer's in carefully controlled research settings.
[03:34.26]However, a new study of about 1,200 patients in Sweden shows they also can work in doctors' offices.
[03:46.19]The findings suggest the blood tests may be more helpful for general care doctors.
[03:52.79]They see many more cases of people with memory problems than specialists do. However, general care doctors have fewer diagnostic tools.
[04:06.13]In the study, patients who visited either a general care doctor or a specialist for memory problems got an early diagnosis using traditional exams.
[04:20.13]They gave blood for testing and got confirmatory spinal taps or brain scans.
[04:27.34]Blood testing is far more accurate, Lund University researchers reported recently at the Alzheimer's Association International Conference in Philadelphia.
[04:40.99]They said that the primary care doctors' first diagnosis was 61 percent accurate and the specialists' first diagnosis 73 percent.
[04:54.10]However, the blood test was 91 percent accurate, their study showed.
[05:00.94]The Journal of the American Medical Association published the study.
[05:06.35]Dr. John Hsiao of the National Institute on Aging said the new tests measure different biomarkers in different ways.
[05:20.03]Doctors and researchers should only use blood tests proven to have a greater than 90 percent accuracy rate, said Alzheimer's Association chief science officer Maria Carrillo.
[05:37.58]Carrillo and Hsiao agreed that the blood tests most likely to provide that accuracy measure what is called p-tau217.
[05:50.10]Schindler helped lead an unusual direct comparison of several kinds of blood tests that came to the same finding.
[06:01.96]The Foundation for the National Institutes of Health financed the work.
[06:08.30]That kind of test measures a form of tau that correlates with how much plaque buildup someone has, Schindler explained.
[06:18.12]A high level signals a strong likelihood the person has Alzheimer's.
[06:26.39]A low level strongly suggests Alzheimer's is not the cause of a patient's thinking problems.
[06:34.17]Several companies are developing p-tau217 tests.
[06:40.00]In the United States, only doctors can order the blood tests from labs.
[06:47.79]The Alzheimer's Association is working on policy suggestions and several companies plan to seek FDA approval, which would clarify correct use.
[07:00.82]For now, Carrillo said doctors should use blood testing only in people with memory problems, after checking the accuracy of the kind they order.
[07:13.62]Especially for primary care physicians, "it really has great potential to help them in sorting out who to give a reassuring message and who to send on to memory specialists," said Dr. Sebastian Palmqvist of Lund University.
[07:32.78]Palmqvist led the Swedish study with Lund's Dr. Oskar Hansson.
[07:40.14]I'm John Russell.
[07:42.24]And I'm Caty Weaver.
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Words in This Story
diagnose - v. to identify a disease from its signs and symptoms
diagnosis - n. the act of identifying a disease from its signs and symptoms
accuracy - n. the quality of being precise or correct
cognitive - adj. of or relating to thinking, reasoning, or remembering
neuron - n. a cell that is the fundamental functional unit of nervous tissue transmitting and receiving nerve impulses
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