Plasma biomarkers may bring new perspectives for the diagnosis of these diseases in Brazil

Dementia has become one of the major public health concerns, particularly in low- and middle-income countries such as Brazil. With an aging population, the demand for accurate diagnoses and treatments for diseases like Alzheimer’s Disease (AD) is expected to rise significantly. Published in Nature Communications, a recent study conducted by researchers from the Instituto D’Or de Pesquisa e Ensino (IDOR) in collaboration with the Federal University of Rio de Janeiro, Neurolife, and Queen’s University presents promising advances in the identification of blood biomarkers that may improve the diagnosis of AD and other types of dementia.

Alzheimer’s Disease is the leading cause of dementia worldwide. With increasing life expectancy, an estimated 70% of people diagnosed with dementia will be living in low- and middle-income countries by 2050. In recent years, scientists have been working to understand the biological mechanisms underlying AD. Part of this research focuses on investigating blood plasma biomarkers that may enable the disease to be detected in a rapid, safe, and accessible manner. This is particularly important for distinguishing AD from other types of dementia.

It is worth noting that recent data from the ELSI-Brasil study demonstrated that approximately 77% of adults with dementia in Brazil remain undiagnosed. Additionally, research on the performance of biomarkers in the Brazilian population is still scarce, unlike the progress seen in high-income countries.

The present study, led by researchers Fernanda Tovar-Moll and Fernanda De Felice, investigated the profile of blood biomarkers in a cohort of 145 patients evaluated at the Memory Clinic of IDOR. These patients were diagnosed with different types of dementia, including AD, amnestic mild cognitive impairment, dementia with Lewy bodies, and vascular dementia, along with cognitively healthy controls.

Luis Santos, the first author of the study, used the Single Molecule Array (SIMOA) platform to analyze blood molecules such as NfL, GFAP, pTau181, and pTau217. These biomarkers have shown effectiveness in the early detection of brain changes related to dementia and may serve as an affordable alternative to expensive tests such as positron emission tomography (PET) and cerebrospinal fluid (CSF) analysis.

The study’s results showed that plasma pTau217 could identify brain changes associated with Alzheimer’s Disease with 94% accuracy. This suggests that it could be an effective tool to aid in diagnosing the disease, particularly in settings where more complex examinations are not available.

Another important finding was that pTau181 was able to distinguish Alzheimer’s Disease from other types of dementia, highlighting its potential to assist physicians in differentiating between neurodegenerative disorders. Furthermore, the combined analysis of biomarkers — such as pTau-to-Aβ42 ratios —demonstrated even better performance, suggesting that combined tests may enhance diagnostic precision and reliability.

The study also underscored the relevance of GFAP, a biomarker linked to cognitive decline in Alzheimer’s patients. Individuals with elevated plasma levels of GFAP and high levels of pTau181 or pTau217 were more likely to exhibit worse cognitive performance compared to those with elevated levels of only one of these biomarkers.

This study represents progress in validating blood biomarkers for the diagnosis of AD and other dementias in Brazil and Latin America, regions where access to tests such as cerebrospinal fluid analysis and PET-CT remains limited. With the development of new therapies, including anti-amyloid antibodies, the ability to diagnose dementia early using accessible biomarkers is becoming increasingly crucial. The introduction of these biomarkers could transform how dementias are diagnosed, helping to reduce underdiagnosis and promoting more effective treatment strategies.