Neurons, unlike most cells, cannot regenerate once they die.
No cruzamento entre ciência e equidade, pesquisadores brasileiros desenvolveram um exame de sangue capaz de identificar o Alzheimer com mais de 90% de precisão — superando o método considerado padrão-ouro por décadas. A descoberta, ancorada na proteína p-tau217, não apenas amplia a janela terapêutica antes que os neurônios se percam de forma irreversível, mas aponta para um futuro em que o diagnóstico avançado deixa de ser privilégio e passa a ser direito. O Brasil, com sua rede pública de saúde, pode se tornar o palco de uma transformação global na forma como a humanidade enfrenta o declínio cognitivo.
- O Alzheimer avança silencioso enquanto o diagnóstico chega tarde demais — e cada neurônio perdido é uma porta que não se reabre.
- Pesquisadores da UFRGS identificaram na proteína p-tau217 um marcador estável no sangue, capaz de distinguir cérebros saudáveis dos afetados pela doença com precisão superior a 90%.
- Uma revisão internacional publicada na Lancet Neurology, com participação de oito brasileiros, analisou mais de 110 estudos e confirmou o p-tau217 como o biomarcador sanguíneo mais promissor para o Alzheimer.
- Enquanto testes privados custam até R$ 3.600 e ficam fora do alcance da maioria, a Iniciativa Brasileira de Biomarcadores busca integrar o exame ao SUS e democratizar o acesso ao diagnóstico precoce.
- A corrida agora não é científica, mas logística: construir a infraestrutura pública capaz de levar esse avanço a clínicas rurais, pequenas cidades e a todos que precisam — antes que o tempo roube mais memórias.
Um exame de sangue desenvolvido por pesquisadores brasileiros identificou o Alzheimer com precisão superior a 90%, superando o exame de líquido cefalorraquidiano que por décadas foi considerado o padrão-ouro do diagnóstico. A descoberta abre caminho para detectar a doença mais cedo — quando o tratamento ainda pode fazer diferença — e para levar esse recurso ao sistema público de saúde.
O estudo foi conduzido na Universidade Federal do Rio Grande do Sul por Willyans Borelli e Eduardo Zimmer, com 59 pacientes de clínicas de memória em Porto Alegre. Os participantes passaram por testes cognitivos, coleta de sangue e líquor, e ressonância magnética. O que os pesquisadores encontraram foi a proteína p-tau217: o marcador mais confiável para distinguir cérebros saudáveis daqueles com as marcas típicas do Alzheimer — placas de amiloide e proteína tau fosforilada. Sua vantagem está na estabilidade: ao contrário de outros biomarcadores, o p-tau217 não oscila com temperatura, horário ou método de coleta, tornando o teste reproduzível em qualquer contexto.
A importância do diagnóstico precoce é biológica e urgente. Neurônios não se regeneram. A janela para intervenção — o período em que é possível retardar o declínio cognitivo — se fecha à medida que as perdas se acumulam. Identificar a doença antes que os sintomas se agravem significa agir enquanto o cérebro ainda pode ser protegido.
No Brasil, testes sanguíneos para Alzheimer já existem no setor privado, mas custam até R$ 3.600 — inacessíveis para a maioria. Borelli e Zimmer lideram a Iniciativa Brasileira de Biomarcadores em Doenças Neurodegenerativas, com o objetivo de tornar o exame parte da política pública de saúde no SUS. Os custos tendem a cair com a escala, e a coleta de sangue pode acontecer em qualquer lugar — de grandes hospitais a postos rurais. A pergunta, dizem os pesquisadores, não é se o teste funciona. É com que velocidade o Brasil conseguirá construir o caminho para que ele chegue a todos.
A blood test developed by Brazilian researchers can identify Alzheimer's disease with better than 90% accuracy—outperforming the cerebrospinal fluid examination that has long been considered the diagnostic gold standard. The finding, published in recent months, opens a path toward catching the disease earlier, when treatment is most effective, and potentially bringing advanced neurological screening within reach of Brazil's public health system.
The research emerged from work at the Federal University of Rio Grande do Sul, where Willyans Borelli and Eduardo Zimmer led a study of 59 patients attending memory clinics in Porto Alegre. Participants included people with Alzheimer's diagnoses, those with vascular dementia, and cognitively healthy individuals. Each underwent cognitive testing, blood and cerebrospinal fluid collection, and magnetic resonance imaging. The researchers were hunting for biomarkers—measurable biological signals—that could reliably flag the disease in blood samples.
What they found was the protein p-tau217. In two separate studies, this marker emerged as the most reliable blood-based indicator for distinguishing healthy brains from those bearing the hallmarks of Alzheimer's: abnormal accumulations of amyloid plaques and phosphorylated tau protein. The protein's appeal lies partly in its stability. Unlike other potential markers that fluctuate with temperature, time of day, or collection method, p-tau217 levels remain consistent in blood samples, making the test reproducible and dependable across different settings and circumstances.
Borelli explained the mechanism to journalists: the protein rises in patients whose brains show the characteristic pathological changes of Alzheimer's, but the exact biological origin of p-tau217 in the bloodstream remains incompletely understood. What matters clinically is that it works. An international review published in September in the Lancet Neurology, authored by 23 researchers including eight Brazilians, analyzed more than 110 studies involving roughly 30,000 people and confirmed that p-tau217 in blood is the most promising biomarker for identifying Alzheimer's.
The timing of detection carries profound weight. Neurons, unlike most cells in the body, cannot regenerate once they die. The window for intervention—the period when treatment can slow or prevent cognitive decline—closes as neuronal loss accumulates. Early identification of amyloid protein in people experiencing memory loss expands that therapeutic window considerably. Borelli emphasized that this advantage could transform how Alzheimer's is managed: catching the disease before symptoms become severe allows doctors to act while the brain still has capacity to be protected.
Today, blood tests for Alzheimer's exist in Brazil's private sector. American tests like PrecivityAD2 are available domestically at costs reaching 3,600 reais—a price that places them beyond most people's reach. Borelli and Zimmer are leading the Brazilian Initiative for Biomarkers in Neurodegenerative Diseases, an effort to establish blood-based screening as official public health policy within Brazil's unified health system. The goal is to democratize access, bringing cutting-edge diagnosis to clinics and hospitals nationwide rather than confining it to private practice.
The economics are favorable. While blood tests for Alzheimer's will never be as cheap as routine hemograms, costs will decline as the technology scales. Unlike the gold-standard cerebrospinal fluid test, which requires specialized facilities and trained personnel, blood draws can happen anywhere—in small towns, rural clinics, primary care offices. Borelli sees no doubt that the test is viable at scale. The question is not whether it can work, but how quickly Brazil can build the infrastructure to make it available to everyone who needs it.
Citações Notáveis
The protein p-tau217 rises in patients whose brains show abnormal accumulations of amyloid plaques and phosphorylated tau protein, the characteristic pathology of Alzheimer's disease.— Willyans Borelli, UFRGS researcher
Blood tests for Alzheimer's are very viable. While costs remain higher than routine blood work, they will decline with use, and unlike the gold-standard test, blood draws can be performed anywhere in the country.— Willyans Borelli
A Conversa do Hearth Outra perspectiva sobre a história
Why does this particular protein, p-tau217, matter more than other markers researchers have looked at?
It's about reliability in practice. Other proteins might be more sensitive in theory, but p-tau217 stays stable in blood no matter when you draw it or how you store it. That consistency is what makes a test actually useful in the real world—you get the same answer whether it's morning or evening, hot or cold.
The source mentions this opens a "therapeutic window." What does that actually mean for a patient?
It means the difference between catching Alzheimer's when you can still slow it down and catching it when the damage is already done. Neurons don't repair themselves. Once they die, they're gone. If you identify the disease early enough, you have time to intervene before too many neurons are lost.
So this test is better than the current standard test. But what makes it revolutionary?
Access. The current gold standard requires a spinal tap—painful, invasive, only available in specialized centers. A blood test can be done anywhere. That's the real breakthrough. It's not just better medicine; it's medicine that can actually reach people.
The article mentions costs of 3,600 reais in private clinics. Is that the barrier to adoption?
It's part of it. But the bigger barrier is that most people can't access the test at all, even at that price. The researchers are trying to get it into the public health system so it's free and available everywhere, not just in wealthy neighborhoods.
What happens next? Is this test going to be available soon?
That depends on whether the Brazilian government commits resources to implement it as policy. The research is solid. The technology works. Now it's a question of will and funding—whether they'll build the infrastructure to make it real.