New blood tests could help doctors diagnose Alzheimer91裸聊视频檚 disease faster and more accurately, researchers reported Sunday 91裸聊视频� but some appear to work far better than others.
It91裸聊视频檚 tricky to tell if memory problems are caused by Alzheimer91裸聊视频檚. That requires confirming one of the disease91裸聊视频檚 hallmark signs 91裸聊视频� buildup of a sticky protein called beta-amyloid 91裸聊视频� with a hard-to-get brain scan or uncomfortable spinal tap. Many patients instead are diagnosed based on symptoms and cognitive exams.
Labs have begun offering a variety of tests that can detect certain signs of Alzheimer91裸聊视频檚 in blood. Scientists are excited by their potential but the tests aren91裸聊视频檛 widely used yet because there91裸聊视频檚 little data to guide doctors about which kind to order and when. The U.S. Food and Drug Administration hasn91裸聊视频檛 formally approved any of them and there91裸聊视频檚 little insurance coverage.
91裸聊视频淲hat tests can we trust?91裸聊视频� asked Dr. Suzanne Schindler, a neurologist at Washington University in St. Louis who91裸聊视频檚 part of a research project examining that. While some are very accurate, 91裸聊视频渙ther tests are not much better than a flip of a coin.91裸聊视频�
Demand for earlier Alzheimer91裸聊视频檚 diagnosis is increasing
More than 6 million people in the United States and millions more around the world have Alzheimer91裸聊视频檚, the most common form of dementia. Its telltale 91裸聊视频渂iomarkers91裸聊视频� are brain-clogging amyloid plaques and abnormal tau protein that leads to neuron-killing tangles.
New drugs, Leqembi and Kisunla, can modestly slow worsening symptoms by removing gunky amyloid from the brain. But they only work in the earliest stages of Alzheimer91裸聊视频檚 and proving patients qualify in time can be difficult. Measuring amyloid in spinal fluid is invasive. A special PET scan to spot plaques is costly and getting an appointment can take months.
Even specialists can struggle to tell if Alzheimer91裸聊视频檚 or something else is to blame for a patient91裸聊视频檚 symptoms.
91裸聊视频淚 have patients not infrequently who I am convinced have Alzheimer91裸聊视频檚 disease and I do testing and it91裸聊视频檚 negative,91裸聊视频� Schindler said.
New study suggests blood tests for Alzheimer91裸聊视频檚 can be simpler and faster
Blood tests so far have been used mostly in carefully controlled research settings. But a new study of about 1,200 patients in Sweden shows they also can work in the real-world bustle of doctors91裸聊视频� offices 91裸聊视频� especially primary care doctors who see far more people with memory problems than specialists but have fewer tools to evaluate them.
In the study, patients who visited either a primary care doctor or a specialist for memory complaints got an initial diagnosis using traditional exams, gave blood for testing and were sent for a confirmatory spinal tap or brain scan.
Blood testing was far more accurate, Lund University researchers reported Sunday at the Alzheimer91裸聊视频檚 Association International Conference in Philadelphia. The primary care doctors91裸聊视频� initial diagnosis was 61% accurate and the specialists91裸聊视频� 73% 91裸聊视频� but the blood test was 91% accurate, according to the findings, which also were published in the Journal of the American Medical Association.
Which blood tests for Alzheimer91裸聊视频檚 work best?
There91裸聊视频檚 almost 91裸聊视频渁 wild West91裸聊视频� in the variety being offered, said Dr. John Hsiao of the National Institute on Aging. They measure different biomarkers, in different ways.
Doctors and researchers should only use blood tests proven to have a greater than 90% accuracy rate, said Alzheimer91裸聊视频檚 Association chief science officer Maria Carrillo.
Today91裸聊视频檚 tests most likely to meet that benchmark measure what91裸聊视频檚 called p-tau217, Carrillo and Hsiao agreed. Schindler helped lead an unusual direct comparison of several kinds of blood tests, funded by the Foundation for the National Institutes of Health, that came to the same conclusion.
That type of test measures a form of tau that correlates with how much plaque buildup someone has, Schindler explained. A high level signals a strong likelihood the person has Alzheimer91裸聊视频檚 while a low level indicates that91裸聊视频檚 probably not the cause of memory loss.
Several companies are developing p-tau217 tests including ALZpath Inc., Roche, Eli Lilly and C2N Diagnostics, which supplied the version used in the Swedish study.
Who should use blood tests for Alzheimer91裸聊视频檚?
Only doctors can order them from labs. The Alzheimer91裸聊视频檚 Association is working on guidelines and several companies plan to seek FDA approval, which would clarify proper use.
For now, Carrillo said doctors should use blood testing only in people with memory problems, after checking the accuracy of the type they order.
Especially for primary care physicians, 91裸聊视频渋t really has great potential to help them in sorting out who to give a reassuring message and who to send on to memory specialists,91裸聊视频� said Dr. Sebastian Palmqvist of Lund University, who led the Swedish study with Lund91裸聊视频檚 Dr. Oskar Hansson.
The tests aren91裸聊视频檛 yet for people who don91裸聊视频檛 have symptoms but worry about Alzheimer91裸聊视频檚 in the family 91裸聊视频� unless it91裸聊视频檚 part of enrollment in research studies, Schindler stressed.
That91裸聊视频檚 partly because amyloid buildup can begin two decades before the first sign of memory problems, and so far there are no preventive steps other than basic advice to eat healthy, exercise and get enough sleep. But there are studies underway testing possible therapies for people at high risk of Alzheimer91裸聊视频檚, and some include blood testing.
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The Associated Press Health and Science Department receives support from the Howard Hughes Medical Institute91裸聊视频檚 Science and Educational Media Group. The AP is solely responsible for all content.
Lauran Neergaard, The Associated Press
