Rachel Klemovitch, Assistant Editor02.26.24
Researchers at Washington University School of Medicine in St. Louis and Lund University in Sweden conducted a test that showed a blood test can be as effective at detecting molecular signs of Alzheimer’s disease as cerebrospinal fluid tests that are approved by the FDA for Alzheimer’s diagnosis.
Washington University researchers developed the blood test, which uses a highly sensitive technique to measure levels of Alzheimer’s proteins in the blood. Results can be found in Nature Medicine.
Identifying Alzheimer’s is important as treatments that can slow the progression of the disease tend to be more effective when started sooner rather than later.
The findings from this study show that a blood test can detect the disease even in patients with mild symptoms accurately as cerebrospinal fluid tests, and it can be used to identify molecular signs when symptoms have not emerged.
“The accuracy of this blood test now enables us to diagnose the presence of Alzheimer’s disease pathology with a single blood sample,” co-senior author Randall J. Bateman, MD, professor of Neurology at Washington University told the press. “This advance will increase accurate diagnoses for many patients.”
Historically, Alzheimer’s has been diagnosed symptomatically, but studies have shown that up to a third of people diagnosed with Alzheimer’s based only on cognitive symptoms are misdiagnosed. Therefore, patients must receive a positive test for amyloid plaques as well as cognitive impairment before being eligible for Alzheimer’s therapies.
Amyloid plaques are unique to Alzheimer’s and are identified through cerebrospinal fluid analyses done by amyloid positron emission tomography (PET) brain scans. This is a test that is not used by doctors for people who do not display cognitive symptoms.
“In the near future, this type of blood test will replace the need for costly and less accessible cerebrospinal fluid and PET imaging tests in specialist memory clinics,” said co-senior author Oskar Hansson, a professor of neurology at Lund University. “Next, we need to determine if the Alzheimer’s blood test also works in primary care. This is currently being investigated in Sweden.”
In 2019, this test has received a “Breakthrough Device” designation from the FDA. This first approved blood test for amyloid in the brain uses mass spectrometry to measure the ratio of two forms of amyloid in the blood. A second blood test was created based on the effects of amyloid accumulation on the brain protein tau. Amyloid in the brain changes the levels of different forms of the tau protein in the blood and the brain.
Measuring the ratio of two types of tau in the blood has been shown to reliably reflect the levels of amyloid in the brain. A test that combines the amyloid and tau blood measures has been marketed by Washington University’s startup C2N Diagnostics, as PrecivityAD2.
Studies for the test included a cohort of 1,422 volunteers at the Swedish BioFINDER-2 and a cohort of 337 volunteers at Washington University’s Charles F. and Joanne Knight Alzheimer Disease Research Center. Groups included people with very mild and mild cognitive symptoms and healthy people to compare to. The blood test results were compared to PET brain scans for amyloid and tau tangles.
The ptau-217 blood test proved to be just as effective as the FDA-approved cerebrospinal fluid tests in the identification of amyloid buildup, with accuracy scores ranging from 95% to 97%. Secondary analysis measured the accuracy of the tests in determining the levels of tau tangles in the brain, which proved superior with accuracy scores of 95% to 98%.
“We now have therapies that have clinical benefits, which is great, but they don’t reverse the loss of neurons in the brain,” Barthélemy said. “What we really want is to treat the disease before people start losing brain cells and showing symptoms.”
“Imagine a person who is 55 or 60 and has a family history of Alzheimer’s or some high-risk genetic variants,” Barthélemy continued. “It would be really valuable to have an easy way to know whether they have amyloid pathology in their brains. If they do, they could come in, maybe once every two or three years, and get a therapy to clear the amyloid out and then never develop dementia at all. We’re still a few years away from such an approach, but I think that’s the future of Alzheimer’s care, and it depends on presymptomatic diagnosis and treatment.”
Washington University researchers developed the blood test, which uses a highly sensitive technique to measure levels of Alzheimer’s proteins in the blood. Results can be found in Nature Medicine.
Identifying Alzheimer’s is important as treatments that can slow the progression of the disease tend to be more effective when started sooner rather than later.
The findings from this study show that a blood test can detect the disease even in patients with mild symptoms accurately as cerebrospinal fluid tests, and it can be used to identify molecular signs when symptoms have not emerged.
“The accuracy of this blood test now enables us to diagnose the presence of Alzheimer’s disease pathology with a single blood sample,” co-senior author Randall J. Bateman, MD, professor of Neurology at Washington University told the press. “This advance will increase accurate diagnoses for many patients.”
Historically, Alzheimer’s has been diagnosed symptomatically, but studies have shown that up to a third of people diagnosed with Alzheimer’s based only on cognitive symptoms are misdiagnosed. Therefore, patients must receive a positive test for amyloid plaques as well as cognitive impairment before being eligible for Alzheimer’s therapies.
Amyloid plaques are unique to Alzheimer’s and are identified through cerebrospinal fluid analyses done by amyloid positron emission tomography (PET) brain scans. This is a test that is not used by doctors for people who do not display cognitive symptoms.
“In the near future, this type of blood test will replace the need for costly and less accessible cerebrospinal fluid and PET imaging tests in specialist memory clinics,” said co-senior author Oskar Hansson, a professor of neurology at Lund University. “Next, we need to determine if the Alzheimer’s blood test also works in primary care. This is currently being investigated in Sweden.”
In 2019, this test has received a “Breakthrough Device” designation from the FDA. This first approved blood test for amyloid in the brain uses mass spectrometry to measure the ratio of two forms of amyloid in the blood. A second blood test was created based on the effects of amyloid accumulation on the brain protein tau. Amyloid in the brain changes the levels of different forms of the tau protein in the blood and the brain.
Measuring the ratio of two types of tau in the blood has been shown to reliably reflect the levels of amyloid in the brain. A test that combines the amyloid and tau blood measures has been marketed by Washington University’s startup C2N Diagnostics, as PrecivityAD2.
Studies for the test included a cohort of 1,422 volunteers at the Swedish BioFINDER-2 and a cohort of 337 volunteers at Washington University’s Charles F. and Joanne Knight Alzheimer Disease Research Center. Groups included people with very mild and mild cognitive symptoms and healthy people to compare to. The blood test results were compared to PET brain scans for amyloid and tau tangles.
The ptau-217 blood test proved to be just as effective as the FDA-approved cerebrospinal fluid tests in the identification of amyloid buildup, with accuracy scores ranging from 95% to 97%. Secondary analysis measured the accuracy of the tests in determining the levels of tau tangles in the brain, which proved superior with accuracy scores of 95% to 98%.
“We now have therapies that have clinical benefits, which is great, but they don’t reverse the loss of neurons in the brain,” Barthélemy said. “What we really want is to treat the disease before people start losing brain cells and showing symptoms.”
“Imagine a person who is 55 or 60 and has a family history of Alzheimer’s or some high-risk genetic variants,” Barthélemy continued. “It would be really valuable to have an easy way to know whether they have amyloid pathology in their brains. If they do, they could come in, maybe once every two or three years, and get a therapy to clear the amyloid out and then never develop dementia at all. We’re still a few years away from such an approach, but I think that’s the future of Alzheimer’s care, and it depends on presymptomatic diagnosis and treatment.”