Recent studies conducted by Brazilian scientists have confirmed the potential of a blood test for diagnosing Alzheimer’s. The analyses highlight the strong performance of the p-tau217 protein as the primary biomarker for distinguishing, through this test, healthy individuals from people with the disease. The goal of the research, supported by the Serrapilheira Institute, is to bring the studies to the Unified Health System (SUS) for large-scale use.
According to Eduardo Zimmer, a researcher at the Federal University of Rio Grande do Sul (UFRGS), supported by the institute, currently in Brazil there are two tests capable of identifying Alzheimer’s: the CSF test, an invasive procedure involving a lumbar puncture using a very fine needle; and the imaging test (tomography). Before that, the only way to detect the possibility of the disease was the clinical exam, usually performed by a neurologist who made the diagnosis based on the patient’s symptoms.
“Both the CSF test and tomography can be requested by the doctor for biomarker-assisted Alzheimer’s diagnosis. The problem is that when we think of a country like Brazil, continental, with 160 million people who depend on the SUS, how are we going to perform these tests on a large scale? A lumbar puncture requires infrastructure, experience, and is usually performed by a neurologist. The imaging test is very expensive to use in the SUS nationwide,” he stated.
The research, signed by 23 researchers including eight Brazilians, analyzed more than 110 studies on the topic involving about 30,000 people, confirming that p-tau217 in the blood is the most promising biomarker for identifying Alzheimer’s disease. In addition to Zimmer, the study includes Wagner Brum, a PhD student and member of the research group at UFRGS, as co-authors.
The results were obtained from analyses of 59 patients, and the tests were compared with the “gold standard,” the CSF test, showing a high level of reliability above 90%, the standard recommended by the World Health Organization (WHO). According to Zimmer, at the same time a group of researchers from the D’Or Institute in Rio de Janeiro and UFRJ (Federal University of Rio de Janeiro), professors Sérgio Ferreira, Fernanda De Felice, and Fernanda Tovar-Moll, published a practically identical study with the same results.
“These are two different regions of the country, with completely different genetics and sociocultural characteristics, and the test worked very well,” he highlighted.
Currently, early diagnosis of Alzheimer’s disease is considered one of the main public health challenges worldwide. According to the WHO, approximately 57 million people worldwide live with some type of dementia—of these, at least 60% have an Alzheimer’s diagnosis. In Brazil, the 2024 National Report on Dementia estimates about 1.8 million people with the disease. The projection is that the number could triple by 2050.
Low Schooling
In the study, the scientists identified that low schooling appears to exacerbate the disease more, reinforcing the hypothesis that socioeconomic and educational factors impact brain aging.
“Low schooling is a very important risk factor for cognitive decline, ranking above age and sex. We conducted this study in Brazil, and the standout factor is low schooling. In the biological context, we understand that a brain exposed to formal education creates more connections. It’s like exercising the brain, making it more resistant to cognitive decline,” the researcher emphasized.
SUS
Diagnosis via blood test is already a reality in the private sector. Tests performed abroad, such as the American PrecivityAD2, are offered in Brazil at a cost that can reach R$ 3,600. Although they offer high accuracy, their high price underscores the importance of developing a national, free alternative.
The researcher explained that, for the test to reach the SUS, it is first necessary to determine if it will have the required performance. Secondly, establish the strategy and logistics for inclusion in the SUS.
“We need various evaluations to understand where the analyses will be performed, when these tests will be used, which population will benefit, and whether it will accelerate diagnosis in the SUS,” he said.
However, before reaching that stage, there is still a path ahead, making it difficult to estimate availability. Definitive results will be available in about two years. Although the disease is more common in people aged 65 and older, studies will begin with individuals over 55.
“We will start the studies with individuals over 55, because we know there is a phase we call the pre-clinical phase of Alzheimer’s disease, when the disease begins to take hold but the individual still has no symptoms. The goal is to also map the prevalence of these individuals,” Zimmer added.
According to the Serrapilheira Institute, the research was published in the journal Molecular Psychiatry, and the results were reinforced in an international review published in September in the Lancet Neurology.
Source: Agência Brasil