Recent studies carried out by Brazilian scientists have confirmed the potential of a blood test for diagnosing Alzheimer’s. The analyzes point to the good performance of the p-tau217 protein as the main biomarker to distinguish, through this test, healthy individuals from people with the disease. The objective of the research, supported by the Serrapilheira Institute, is to take 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 cerebrospinal fluid test, an invasive procedure in which a lumbar puncture is performed using a very thin needle; and imaging examination (tomography). Before that, the only way to detect the possibility of the disease was a clinical examination, normally carried out by a neurologist who made a diagnosis based on the patient’s symptoms.
“Both the cerebrospinal fluid test and the tomography can be requested by the doctor for the diagnosis of Alzheimer’s disease assisted by biomarkers. The problem is that when we think about a country like Brazil, continental, with 160 million people who depend on the SUS, how are we going to carry out these tests on a large scale? A lumbar puncture requires infrastructure, experience and it is usually the neurologist who does it. The imaging test is very expensive to use in the SUS throughout the country”, he stated.
The research, signed by 23 researchers, including eight Brazilians, analyzed more than 110 studies on the subject with around 30 thousand 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 doctoral student and member of the research group at UFRGS, as co-authors.
Brazilian researcher Eduardo Zimmer, from UFRGS, participates in a study on the diagnosis of Alzheimer’s – Photo Serrapilheira Institute/Disclosure
The results were obtained from analyzes 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 Instituto D’Or, in Rio de Janeiro, and UFRJ (Federal University of Rio de Janeiro), professors Sérgio Ferreira, Fernanda De Felice and Fernanda Tovar-Moll, returned a practically identical study with the same results.
“They 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 in the world. According to the WHO, approximately 57 million people in the world live with some type of dementia — of these, at least 60% are diagnosed with Alzheimer’s. In Brazil, the 2024 National Report on Dementia estimates around 1.8 million people with the disease. The forecast is that the number could triple by 2050.
Low education
In the study, scientists identified that low education seems to make the disease more severe, reinforcing the hypothesis that socioeconomic and educational factors impact brain aging.
“Low education is a very important risk factor for cognitive decline, exceeding age and gender. We carried out this study in Brazil and the first place to be highlighted is low education. In the biological context, we understand that the brain that is exposed to formal education creates more connections. It is as if we exercised the brain, which becomes more resistant to cognitive decline”, highlighted the researcher.
SUS
Diagnosis by blood test is already a reality in the private network. Tests carried out abroad, such as the American PrecivityAD2, are offered in Brazil at a cost that can reach R$3,600. Although they present high precision, their high price reinforces the importance of developing a national and free alternative.
The researcher explained that, for the exam to reach the SUS, it is first necessary to understand whether it will have the necessary performance. Secondly, establish the strategy and logistics for inclusion in the SUS.
“We need several assessments to understand where the analyzes will be carried out, when these tests will be used, which population will benefit, whether or not the diagnosis in the SUS will be accelerated”, he said.
However, before reaching this stage there is still a way to go, which makes it difficult to estimate this availability. Final results will be available in approximately two years. Although the disease is more common in people over 65 years of age, studies will be initiated in people over 55 years of age.
“We are going to start studies with individuals over 55 years of age, because we know that there is a phase that we call pre-clinical Alzheimer’s disease, which is when the disease begins to take hold, but the individual still has no symptoms. The idea is that we can also map the prevalence of these individuals”, added Zimmer.
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 journal Lancet Neurology.
