New Blood Test May Detect Alzheimer’s Disease Early

Emma Johnson

Written by Emma Johnson


Alzheimer’s disease figures prominently as the most common form of dementia, affecting millions worldwide. Its prevalence is on an alarming rise with experts predicting a surge in the affected population over the coming decades. This growing health crisis underscores the urgency for early detection and treatment, which can significantly alter the disease’s trajectory and improve quality of life for those affected.

Research in the field of Alzheimer’s has increasingly concentrated on early diagnosis, with the understanding that interventions are most potent when initiated in the disease’s nascent stages. As such, the scientific community has been diligently working to identify biomarkers that could signal the onset of Alzheimer’s well before the symptoms become overt.

The Quest for Accessible Diagnostic Biomarkers

Biomarkers have long been considered the holy grail for early detection of Alzheimer’s. Traditionally, these markers have been detected in the cerebrospinal fluid (CSF) of patients, requiring an invasive procedure known as a lumbar puncture. However, a groundbreaking study has sparked hope by identifying Alzheimer’s biomarkers in the blood, paving the way for simpler, less invasive testing methods.

The potential for blood tests to detect Alzheimer’s early could be a game-changer in the fight against dementia, which currently affects around 60 million people globally. With projections estimating a staggering increase to over 150 million individuals by 2050, the need for accessible and earlier diagnostic tools is more pressing than ever.

Alzheimer’s Disease: Symptoms and Pathology

Alzheimer’s accounts for 60-80% of all dementia cases, presenting with a spectrum of symptoms ranging from memory loss to cognitive deficits, recognition issues, spatial awareness problems, and changes in personality or behavior. The disease is pathologically characterized by the presence of amyloid plaques and tau tangles within the brain, which are believed to disrupt the normal functioning of nerve cells.

Emerging treatments, such as lecanemab, donanemab, and aducanumab, offer a ray of hope by clearing these amyloid plaques and potentially slowing cognitive decline. The efficacy of these treatments is markedly higher when they are administered early in the disease’s progression, further emphasizing the importance of early and accurate diagnosis.

Breaking New Ground in Biomarker Research

Current research indicates that CSF biomarkers can reveal the presence of Alzheimer’s in its early stages, as well as during mild cognitive impairment and the later stages of the disease. Specifically, decreased levels of beta-amyloid-42 in CSF have been linked to the buildup of amyloid plaques, while increased levels of tau protein are associated with the development of Alzheimer’s.

A pivotal study involving participants aged 60-85 from diverse ethnic backgrounds categorized subjects into groups based on cognitive health, ranging from cognitively healthy to those with mild cognitive impairment and mild Alzheimer’s disease. The participants underwent comprehensive testing, including cognitive assessments, blood sampling, PET scans or CSF sampling, and additional blood sampling over three lab visits.

Insights from the Blood-Based Biomarker Study

The study found no correlation between beta-amyloid-40 or total tau (t-tau) in blood and amyloid positivity in PET scans. However, it did reveal strong relationships with beta-amyloid-42, phosphorylated tau at threonine 181 (p-tau181), and phosphorylated tau at threonine 217 (p-tau217). Blood tests showed that individuals with amyloid positivity in PET scans had lower levels of beta-amyloid-42 and higher levels of p-tau181 and p-tau217.

Notably, the research brought to light that non-Hispanic Black participants had significantly lower average concentrations of these biomarkers as compared to non-Hispanic white participants. This finding emphasizes the importance of considering ethnic and racial backgrounds in the development and interpretation of diagnostic tests for Alzheimer’s.

Experts like Dr. Heather Snyder have pointed out that p-tau217, p-tau181, and the ratio of beta-amyloid-42 to beta-amyloid-40 are significant predictors of amyloid positivity across ethnic groups. This suggests that these blood-based biomarkers could serve as a reliable method for identifying individuals at risk for Alzheimer’s, irrespective of their ethnic background.

Debating the Clinical Utility of Blood Tests for Alzheimer’s

While the study’s findings are promising, not all experts are fully convinced of the clinical usefulness of blood tests for Alzheimer’s diagnosis. Skepticism remains, as some clinicians, including Dr. Clifford Segil, question the practicality and reliability of using blood tests in a real-world clinical setting.

Contrastingly, Dr. Snyder has highlighted the accumulating evidence that equates blood-based biomarkers with the detection methods currently used in CSF and imaging. These blood tests could potentially signal the need for additional investigations in individuals who exhibit symptoms of cognitive decline, thereby serving as an initial screening tool.

Seeing the study as a pivotal advancement, Dr. Emer MacSweeney believes that having faster, more accurate diagnostic capabilities for Alzheimer’s will be instrumental in the timely implementation of treatment with new medications. This could significantly alter the course of the disease, offering hope to millions of patients and their families.

The Future of Alzheimer’s Diagnosis and Treatment

The research on blood-based biomarkers for Alzheimer’s represents a breakthrough that has the potential to revolutionize the diagnosis and treatment of this debilitating disease. As science continues to advance, the hope is that these findings will lead to widely accessible tests that can diagnose Alzheimer’s at its earliest stages, affording patients the benefit of receiving treatment when it is most effective.

This progress in Alzheimer’s research not only promises improvements in patient care but also offers a glimpse into a future where the devastating impact of dementia could be significantly mitigated. Ultimately, the development of simple blood tests for Alzheimer’s biomarkers stands as a testament to the relentless pursuit of innovation in the face of one of the most challenging health issues of our time.