Blood test for Alzheimer's arrives in Brazil: see who can do it, how much it costs, and what the result reveals

Photo: Disclosure A blood test capable of indicating whether the brain has the biological marks of Alzheimer is being offered in Brazil starting this Thursday (15), currently in a single service: the Moinhos de Vento Hospital in Porto Alegre (RS). The test can dispense, in most cases, the lumbar puncture or imaging examination used today to confirm the disease. The test, which measures the protein p-tau217, is available in the private network for an estimated cost of about R$ 3 thousand. It is intended only for people who already have symptoms and clinical suspicion of Alzheimer's. A positive result alone is not enough to affirm that there is dementia caused by the disease, and the arrival at the Unified Health System (SUS) has no date. The Ministry of Health reports that there was no demand for evaluation of the test by the National Commission for the Incorporation of Technologies into SUS (Conitec), a step required for a technology to enter the public network. A clue in the blood about what is happening in the brain p-tau217 is a chemically modified version of the tau protein, present in nerve cells. Its levels in the blood follow the accumulation of beta-amyloid plaques, a protein that deposits in the brain and is one of the biological marks of Alzheimer's. The test, therefore, does not measure dementia itself, but rather an indirect signal of these changes. The analysis is done on automated equipment, a characteristic that, according to the authors of one of the main studies on the test, favors similar results between different laboratories. The result can be positive, negative, or inconclusive. Eduardo Zimmer, head of research at the Neurosciences Unit of the Moinhos de Vento Hospital and responsible for the implementation of the test, estimates that 15% to 20% of tests fall into this intermediate range. In these cases, the doctor may request a PET (positron emission tomography) or analysis of the cerebrospinal fluid, or repeat the blood test after 12 months. The performance of the Lumipulse platform, from the Belgian manufacturer Fujirebio, was evaluated in a study published in 2025 in the journal Nature Medicine. The research included 1,767 people with cognitive symptoms treated in Sweden, Spain, and Italy. The researchers compared the result of the blood test with that of cerebrospinal fluid analysis, the lumbar puncture used as a reference to confirm the change. With a single cutoff point, the value that separates the positive from the negative result, the blood coincided with the cerebrospinal fluid in 89% to 91% of patients from specialized services. With two cutoff points, the coincidence increased to 92% to 94%, at the cost of leaving 12% to 17% of participants without a defined answer. Zimmer states that the sensitivity and specificity of the test are over 90%, meaning it is correct in both pointing out who has the alteration and ruling out those who do not. According to him, the validation done in the hospital with blood and cerebrospinal fluid samples reached 0.95 on a scale where 1 represents perfect accuracy, and more than a thousand measurements have already been performed in Porto Alegre. This local data has not yet undergone peer review: the validation article will be released this week as a preprint, already submitted to a scientific journal, and the analysis of the thousand measurements is ongoing. Anvisa regularized the Lumipulse G pTau 217 Plasma product family on August 17. Photo: Disclosure Who can take the test The test is intended for the investigation of the disease in its clinical phase, when symptoms have already appeared, and the request comes from the doctor who follows the patient. Zimmer explains that the usefulness is to provide more security to the specialist who wants to confirm the cause of the condition or who has doubts about the diagnosis. According to the package insert, the test is valid for people over 50 years old. Below this age, the meaning of the result is unknown because the test has not been tested in this group. Renato Anghinah, full professor of neurology at the ABC School of Medicine and lecturer at the Faculty of Medicine of the University of São Paulo (USP), states that the request only makes sense when the complaint has already been confirmed by tests showing some decline, however minimal. This condition may correspond to mild cognitive impairment, a change that does not yet constitute dementia, or early-stage Alzheimer's. A single complaint of forgetfulness, without other signs, does not justify the test, he says. In those without symptoms, a positive result has no established meaning. Zimmer recalls that the test's ability to anticipate the onset of the disease is still under evaluation, and there is no approved therapy for this stage, although large studies investigate whether removing amyloid plaques before symptoms appear would bring benefits. The test shows the presence of biological changes, and the diagnosis depends on putting them together with the clinical picture. Anghinah compares the process to a puzzle where the blood measurement is one of the pieces, alongside other tests, to finalize the diagnosis and choose the treatment. Errors exist. - In the study, with a single cutoff point, between 89% and 95% of positive results in specialized services indicated the alteration. - The proportion of correct negatives varied from 77% to 90% depending on the group, meaning that in some of them, one in every four negative results hid the alteration. - Accuracy was also lower in people aged 80 or older (83%). The use of two cutoff points increased accuracy, and the authors indicate that this approach may be necessary for the test to work in isolation, especially in the elderly. The people evaluated in the study are European, and Brazilian validation has not yet been published. A simple alternative to expensive and invasive tests Today, confirming the biological changes of Alzheimer's in a living patient depends mainly on two methods. - Amyloid PET is an imaging examination of nuclear medicine that maps the accumulation of the protein in the brain. - Cerebrospinal fluid analysis, the fluid that surrounds the brain and spinal cord, requires a lumbar puncture for collection. Anghinah observes that the three methods have high accuracy, around 90% in the case of the blood test, and that the change is not in the accuracy of the diagnosis. The gain is in access. PET requires nuclear medicine infrastructure and has a high cost, which leaves few people with access. The puncture is invasive and uncomfortable. The blood test offers comparable accuracy with less invasiveness and lower cost. Zimmer goes further and argues that the test replaces PET and cerebrospinal fluid in all diagnostic indications, with two reservations: inconclusive results and the decision to suspend therapy with anti-amyloid antibodies, for which only PET is used. An uncertain path to the SUS The National Health Surveillance Agency (Anvisa) regularized the Lumipulse G pTau 217 Plasma product family, imported by VR Medical, on August 17. The measurement itself is not new, notes Anghinah: what changed was the validation by Anvisa, without which the result did not have value, for example, in legal matters. Before that, whoever wanted an equivalent blood test had to send the sample to a laboratory in the United States, according to Zimmer. For now, the offer is private. The hospital says it plans to integrate the test into health plans in 2026, without informing operators or dates, and coverage is not confirmed. For the SUS, the hospital's communication speaks of the expectation that the technology will be evaluated in the public system this year through partnerships in the Public Health System Development Support Program (Proadi-SUS). The program allows hospitals of recognized excellence to carry out projects of interest to the public network. The Ministry of Health reports that these projects are submitted by public call, in three-year cycles, and that there are currently no projects in execution with this technology. The ministry adds that Conitec evaluates efficacy, safety, cost-effectiveness, and budgetary impact before any incorporation, and that no demand for the p-tau217 test has reached the body so far. Thus, there is a distance between the hospital's expectation and what the government records. Zimmer acknowledges that cost-effectiveness needs to be evaluated in the SUS. His hypothesis is that the test will improve diagnosis and management in specialized care, and he does not see the laboratory network as an obstacle, because large centers are already being equipped. Anghinah believes that the test will eventually be made available, but says it will need to prove itself more economically competitive than what is already used. In university services, for example, cerebrospinal fluid is available. The process includes public consultations. Gain for those who receive the diagnosis earlier "For the patient, the concrete benefit is to know with more certainty, and possibly sooner, what causes the symptoms," says Zimmer. "The investigation is usually long, and the blood test allows the specialist to finalize the diagnosis more quickly. The sooner the disease is identified, the greater the treatment options." Anghinah explains that there are currently therapies for the initial stages. In Brazil there are two drugs, donanemab and lecanemab, which, when the diagnosis is made very early, can reduce the speed of disease progression by 20% to 30% in some patients, with better results in others. The effect described is to slow down the evolution, not to stop the disease. Frequent forgetfulness requires a medical consultation Whoever notices repeated forgetfulness should seek a health professional, generally a neurologist, Anghinah advises. Geriatricians and psychiatrists also act in this area. The test is prescribed by the doctor, who decides, after evaluation and cognitive tests, whether it is indicated. While the test is not yet evaluated in the public system, the diagnosis in the SUS follows clinical evaluation and laboratory and imaging tests, such as computed tomography and magnetic resonance imaging, the Ministry of Health informed. Whether and when the test will reach the public network will depend on cost-effectiveness analyses and a formal request that does not yet exist.