Blood test for clinical diagnosis of Alzheimer's unprecedented in new guidelines

The Alzheimer's Association released its first comprehensive clinical practice guidelines for the diagnosis, treatment, and care of Alzheimer's disease (AD) at the end of July. This landmark document places particular emphasis on blood-based biomarker testing as a core diagnostic tool for patients presenting with cognitive impairment.

Biomarker Assays for Diagnosis

The guidelines focus on detecting abnormal forms of tau and amyloid-beta proteins, both established biological hallmarks of Alzheimer's disease. Blood-based biomarker assays provide a far less invasive and more accessible alternative to conventional diagnostics, which often involve high costs or discomfort for patients.

"For the first time, we have a rigorously evidence-based framework that allows clinicians to use blood biomarker tests with confidence and consistency," remarked Maria C. Carrillo, PhD, the Association's Chief Science Officer and a co-author of the guidelines.

These guidelines are aimed primarily at specialists evaluating patients with cognitive impairment in memory care settings. They crucially stress that blood test results must always be interpreted within the context of a comprehensive clinical evaluation.

Degenerative Progression of AD

Alzheimer's disease (AD) is a progressive neurodegenerative disorder of the central nervous system, typically manifesting in late or pre-late life. It is characterized by gradual deterioration in cognition and behavior, and accounts for 60% to 80% of all dementia cases worldwide, as stated in the 2024 Alzheimer's disease facts and figures by the Alzheimer's Association.

Preclinical Alzheimer study revealed that pathophysiological changes in the brain often precede clinical symptoms by 15 to 20 years, meaning that disease processes are underway long before memory loss or confusion become apparent. Research indicates that timely detection, followed by early intervention, can produce meaningful clinical benefits, with some even a return to normal cognitive function.

Current Diagnostic Limitations

Traditional diagnostic methods each carry significant limitations. Cognitive function assessment scales are highly dependent on the examiner's subjective judgment. Cerebrospinal fluid (CSF) biomarker testing, amyloid positron emission tomography (PET) scans, all involve procedural drawbacks such as invasiveness, radiation exposure, and considerable expense.

PET brain scans, while accurate, are prohibitively costly and therefore rarely used for early screening. Lumbar puncture, although highly informative, is invasive and often poorly tolerated, especially among older individuals. Few people are willing to use this invasive method for diagnosis and prevention before obvious dementia symptoms appear. These factors limit the feasibility of scaling such tests for community-level or nationwide screening programs. As a result, a large proportion of at-risk individuals remain undiagnosed until symptoms are well advanced.

Blood Testing Breakthrough

Recent advances in biomarker science have positioned blood testing as a transformative tool for early Alzheimer's detection. The U.S. FDA approved Lumipulse G, the first in vitro diagnostic test capable of aiding in AD diagnosis through blood-based analysis, in May this year.

In China, BGI Genomics has developed its own blood-based test for Alzheimer's disease and other cognitive disorders after receiving China's national regulatory approval in April 2024. This test looks for five key signs in the blood, including specific forms of tau and amyloid proteins, along with other nerve-related indicators, that together give doctors a clearer picture of what's happening in the brain.

Studies show blood tests can match the accuracy of more invasive methods, but at a fraction of the cost and with far less discomfort. This makes them more practical for routine check-ups, early screening, and ongoing monitoring, especially for older adults.

Some of the latest drugs, such as donanemab and lecanemab, are designed to target the build-up of amyloid proteins in the brain, one of the key changes linked to the disease. Early studies suggest they may slow or even pause the progression of symptoms for some patients.

However, these treatments are not without risks. A person's genetic make-up can affect how they react to the drugs. Accoriding to Alzheimer's Research UK, people who inherit two copies of the APOE4 gene, may face a much higher risk of side effects like brain swelling or small brain bleeds. Products such as BGI Genomics' Alzheimer's Disease Risk Genetic Testing, offers proactive healthcare solution for early detection and prevention with APOE Genotyping Testing.

Genetic testing, including APOE genotyping, should be integrated with biomarker-based screening to guide individualized treatment decisions. Ultimately, effective prevention and control of Alzheimer's disease will require combining early risk identification with targeted therapeutic interventions, a strategy that could significantly alter the trajectory of the disease.

About Alzheimer's Disease Risk Genetic Testing

BGI Genomics' Alzheimer's Disease Risk Genetic Testing (APOE Genotyping Testing) uses MALDI-TOF MS technology to analyze two APOE gene loci, rs429358 and rs7412, aiding clinicians in evaluating the likelihood and progression of Alzheimer's disease. The test can provide results that guide doctors and patients in making appropriate lifestyle changes.

About BGI Genomics

BGI Genomics, headquartered in Shenzhen, China, is the world's leading integrated solutions provider of precision medicine. Our services cover more than 100 countries and regions, involving more than 2,300 medical institutions. In July 2017, as a subsidiary of BGI Group, BGI Genomics (300676.SZ) was officially listed on the Shenzhen Stock Exchange.