Research shows potential of using blood tests to predict Alzheimer’s disease

SINGAPORE – The possibility of having a screening tool to predict Alzheimer’s disease (AD) is becoming increasingly real as more research supporting its use emerges. This includes a recent Lancet study that demonstrates the potential of detecting biological clues of AD among healthy middle-aged adults using blood tests.

Finding these early biomarkers years before dementia sets in will serve as a risk predictor rather than a formal diagnosis. The goal would be to intervene early to disrupt the timeline of the disease.

There is currently no cure for the debilitating neurodegenerative condition, although new disease-modifying drugs can help to delay its progression if caught early in people already showing cognitive symptoms.

The latest AD research shows that people with no cognitive symptoms but who were found to have biological changes of AD, such as the blood-based biomarker pTau217, show a higher risk of future cognitive impairment and accelerated cognitive decline.

AD is driven by the toxic build-up of amyloid-beta (Aβ) protein plaques and tau protein tangles in the brain. Previous studies have shown that these biological changes start accumulating decades before symptoms appear.

Most studies on AD biomarkers were done in Europe and North America with a predominantly Caucasian population. But Singapore institutions are actively involved in studying how these biomarkers perform in its own diverse population.

In March 2026, the National Neuroscience Institute (NNI) and the Duke-NUS Medical School published a paper on the real-world performance of pTau217.

The study found that the cut-off points of pTau217 were highly consistent with those reported in Western cohorts, supporting their broader applicability across populations, said Adeline Ng, an associate professor and senior consultant at the Department of Neurology in NNI.

“While earlier studies have demonstrated the promise of pTau217 in research cohorts, this study is among the first locally to evaluate its performance in a real-world tertiary memory clinic setting, where patients are more diverse,” she said. For example, they can have mixed dementia such as AD and vascular, which is reflective of everyday clinical practice.

The United States Food and Drug Administration approved blood tests to aid in the diagnosis of AD in 2025, while in Singapore, the NNI uses the pTau217 blood test for clinical and research purposes for patients with cognitive symptoms.

The potential use of such tests for widespread testing in the community can open up a critical window for timely interventions, but challenges remain.

“Blood tests for Alzheimer’s disease have improved dramatically and can identify early biological changes associated with the disease. However, a positive test does not necessarily mean someone will develop dementia,” said Anna Barron, an associate professor at Nanyang Technological University’s Lee Kong Chian School of Medicine, who studies the neurobiology of ageing and disease.

“Distinguishing those at genuine risk from false positives will be a key challenge before these tests can be used for widespread screening in healthy populations,” she said. There is also a need to validate the tests across diverse demographics, she added.

Ng said it is important to determine whether a positive result with minimal or no cognitive impairment is diagnostic of AD, as this could have knock-on implications, for example, on insurability and employment. Scientific opinion is currently divided on this.

“Using pTau217 as a screening test in people without symptoms is not recommended at this stage, because the implications of detecting Alzheimer’s pathology before symptoms develop are complex and require careful counselling, follow-up and treatment considerations,” she said.

For now, the greatest value of these tests is likely to be in supporting the diagnosis of individuals showing early symptoms of cognitive impairment, the two experts said.

Blood-based biomarkers such as pTau217 have strong potential as triaging tools, helping clinicians identify patients who are more likely to have AD pathology and who may benefit from further confirmatory testing or closer follow-up, Ng said.

This could reduce reliance on costly amyloid PET scans or invasive lumbar punctures, particularly in settings where these tests are not readily available, Ng added. The blood tests are not yet approved locally to replace these established methods.

Ng said NNI is currently in the planning stages of a pilot study with primary care physicians to validate the use of an AD blood-biomarker test in patients with cognitive issues. The aim is to assess if this test can be used as a triaging tool for patients with cognitive symptoms who are found to be at higher risk of AD, so they can be referred to specialist memory clinics for earlier evaluation and specialist care, she said.

Meanwhile, scientists are studying whether treating patients with early biological markers of AD but no symptoms can prevent or delay cognitive decline.

Clinical trials under way include a phase three clinical trial testing donanemab – a monoclonal antibody that targets amyloid plaques in the brain – in patients who show early biological signs of AD but have not yet developed symptoms like memory loss or confusion. Donanemab is a prescription medication in Singapore for the treatment of early symptomatic AD.