summary: New research reveals that highly accurate blood tests for Alzheimer’s disease could improve diagnosis and facilitate access to treatment and research. These tests measure biomarkers such as phosphorylated tau, which correlate with cognitive decline and brain atrophy.
“If implemented at the point of care, such a blood test could significantly shorten waiting times for a diagnosis and allow earlier identification of patients for new treatments. This study highlights the potential for blood tests to transform the treatment of Alzheimer’s disease.”
Key Facts:
- Blood tests for Alzheimer’s disease measure biomarkers such as phosphorylated tau.
- These tests greatly improve the accuracy and speed of diagnosis.
- Early detection through blood tests can lead to earlier treatment and participation in research.
sauce: Alzheimer’s Association
A highly accurate blood test for Alzheimer’s disease is closer to use in doctors’ offices, but new research suggests it could revolutionize diagnostic accuracy and provide a cleaner, faster path to research enrollment and treatment, according to data presented today at the Alzheimer’s Association International Conference.® (AAIC®) It will be held in 2024 in Philadelphia and online.
Dementia is often diagnosed late, and even when a doctor does, many people are unaware or unaware of their diagnosis. Alzheimer’s Disease Facts and Figures 2024 report.
Research has demonstrated that a blood test for Alzheimer’s disease can provide clinicians with a platform to greatly improve accuracy and reliability, increase accessibility and enhance communication.
The blood tests that show the most promise for identifying brain changes linked to Alzheimer’s assess the phosphorylated tau (p-tau) protein, a biomarker for Alzheimer’s that can build up before patients show signs of cognitive impairment.
A specific marker, p-tau217, increases over time correlate with worsening cognitive function and brain atrophy. p-tau217 testing also predicts the likelihood of amyloid plaques in the brain, another biomarker for Alzheimer’s disease and the target of recently approved treatments.
“The blood test, if (a) confirmed to be more than 90 percent accurate in large populations and (b) made more widely available, shows the potential to improve and potentially redefine the recruitment process and diagnostic testing for Alzheimer’s disease clinical trials,” said Dr. Maria C. Carillo, chief scientific officer and medical director of the Alzheimer’s Association.
“Currently, primary and secondary care doctors must use a combination of cognitive testing and blood or other biomarker tests to diagnose Alzheimer’s, but blood tests have the potential to improve the accuracy of early diagnosis and maximise the chances of receiving Alzheimer’s treatment as early as possible for better outcomes.”
When considering using blood tests: Alzheimer’s Association Recommendations for Appropriate Use of Blood Biomarkers in Alzheimer’s Disease It needs to be followed carefully.
To help providers incorporate Alzheimer’s blood testing into clinical practice, the Association is convening a panel of clinical and subject matter experts to lead the development of clinical practice guidelines on the use of blood biomarkers in Alzheimer’s, which will be previewed at AAIC 2024.
Blood test could improve diagnosis for primary care and Alzheimer’s specialists
A large-scale study reported for the first time at AAIC 2024 shows that a blood test can detect Alzheimer’s disease more accurately than primary care physicians or specialists using traditional diagnostic methods.
In this study, 1,213 patients were tested with the PrecivityAD2 test (known as “APS2”), which uses a combination of (1) the ratio of plasma phosphorylated to non-phosphorylated tau 217 (known as %p-tau217) and (2) the ratio of the two types of amyloid (Aβ42/Aβ40), which in this study significantly outperformed clinician-administered tests.
- Among 698 patients seen at a memory clinic, the APS2 was about 90% accurate at identifying Alzheimer’s disease, compared with 73% by specialists.
- Among 515 patients seen in primary care, the APS2 was also about 90% accurate: Primary care physicians were 63% accurate in identifying Alzheimer’s disease.
The researchers observed that the APS2 test was highly accurate, even in patients with comorbidities such as kidney disease, which are common among older patients seen by primary care physicians.
“Notably, these were results from blood samples sent for analysis every two weeks from primary care units, similar to routine clinical practice,” said lead author Sebastian Palmqvist, MD, PhD, of Lund University in Lund, Sweden.
“These results were particularly striking given that the older adult population attending primary care often has medical conditions that affect or alter p-tau217 concentrations.”
“We believe this is a major step towards the global clinical implementation of a blood test for Alzheimer’s disease,” said lead author Oskar Hansson, M.D., also of Lund University. “This highlights the need for biomarkers for Alzheimer’s disease to make more accurate diagnoses.”
“Next steps include establishing clear guidelines for how blood tests for Alzheimer’s disease can be used in clinical practice, ideally by implementing these tests first in specialist care and then in primary care. This work is currently underway.”
The study reported at AAIC was funded by the Alzheimer’s Association. Journal of the American Medical Association.
Study shows blood test could identify people without cognitive impairment in clinical trials
Including people in the early stages of Alzheimer’s disease in clinical trials could help identify treatments that are effective when symptoms are mild or absent. A study reported at AAIC 2024 found that the p-tau217 blood test could be a simple and accurate selection tool to identify cognitively unimpaired patients who are likely to have amyloid-β plaques in their brains.
The researchers analyzed plasma p-tau217 and samples from 2,718 cognitively unimpaired participants across 10 different studies who had amyloid-beta PET images or CSF samples available. They found that plasma p-tau217 reliably predicted (in the range of 79-86%) the likelihood that cognitively unimpaired people would test positive for amyloid-beta pathology on an amyloid PET scan or CSF biomarker.
Adding the results of an amyloid-beta CSF test or an amyloid-beta PET scan to the analysis following a positive blood sample improves the positive prediction to over 90%, improving confidence in the presence of amyloid in the brain using plasma p-tau217 testing.
“If these figures are plausible and can be replicated and confirmed in other independent laboratories, this approach could reduce the need for lumbar punctures and PET scans to diagnose Alzheimer’s disease by 80 or even 90 percent,” said Dr. Gemma Salvado, lead author of the study and associate research fellow at Lund University.
“Our findings support that p-tau217 positivity in plasma alone may be sufficient to select amyloid-positive participants without cognitive impairment in many clinical trials.”
Blood test could drastically shorten wait times for Alzheimer’s diagnosis and treatment
Approved Alzheimer’s drugs must be indicated for patients with mild cognitive impairment due to Alzheimer’s disease or mild Alzheimer’s dementia and must have a confirmed amyloid beta biology in the brain, so it is important to identify patients who may benefit from a drug as early as possible in the disease progression.
Currently, there are limited numbers of Alzheimer’s disease specialists and inconsistent and often inequitable access to the expertise required for PET imaging and CSF analysis, which often results in long wait times to complete comprehensive testing to diagnose Alzheimer’s disease.
Research reported at AAIC 2024 suggests that the use of high-performance blood tests in primary care could identify potential Alzheimer’s patients much earlier, allowing experts to determine whether they might be eligible for new treatments.
The researchers used established predictive models to forecast wait times for people eligible for treatment, taking into account the limited number of Alzheimer’s specialists and an ageing population.
The model incorporated projections for the U.S. population aged 55 and over from 2023 to 2032 and compared two scenarios. In the first, primary care clinicians would decide whether to refer patients to Alzheimer’s specialists based on the results of a simple cognitive test.
Second, we would also take into account the results of high-powered blood tests and assume that individuals who test positive for early cognitive impairment would be given blood tests in primary care and that referrals to specialist care would be made based on the test results.
According to the model, by 2033, people would have to wait an average of nearly six years (70 months) to find out whether they could receive new Alzheimer’s treatments if their doctors only used simple cognitive assessments to make referrals.
If a blood test could rule out Alzheimer’s, the average wait time for Alzheimer’s patients would drop to 13 months, as significantly fewer patients would need to see a specialist.
The researchers also concluded that if blood tests and brief cognitive assessments were used at the primary care level to determine a likely Alzheimer’s diagnosis, waiting times to determine eligibility for new treatments would be reduced to an average of less than six months, due to reduced demand for Alzheimer’s specialists and more capacity being made available for CSF and PET scans.
“Our findings suggest that using a blood test to identify potential candidates for treatment could make a big difference in treating people with early-stage Alzheimer’s disease,” said Soren Mattke, MD, PhD, lead author of the study and director of the Brain Health Observatory at the University of Southern California in Los Angeles.
“Currently, it takes a long time to receive a diagnosis, meaning that patients who could be candidates for treatment fall outside of the treatment window. An easily available blood test could help solve this problem.”
About this Alzheimer’s research news
author: AAIC 2024 Press Office
sauce: Alzheimer’s Association
contact: AAIC 2024 Press Office – Alzheimer’s Association
image: Image courtesy of Neuroscience News
Original Research: The survey results were presented at AAIC 2024.
