This week, Brazil starts offering an unprecedented blood test capable of offering a diagnosis of Alzheimer’s in the early stages. The North American PrecivityAD2 test detects proteins that indicate the presence of cerebral amyloid plaques, a characteristic of the disease.
The exam costs around R$3,600 and must be requested by a doctor — the procedure is not yet available through health plans or the Unified Health System (SUS).
The testing is carried out in Brazil by the brand Fleury Medicina e Saúde in partnership with the manufacturer C2N Diagnostics and is not a screening exam, that is, it is not recommended for check-ups, but rather for people who present signs of cognitive decline.
The samples are collected and prepared at the Fleury technical center and sent for analysis in the United States. The result is released in around 20 days.
The Fleury brand should offer the test in its network gradually, starting in São Paulo and expanding to units located in Maranhão, Rio Grande do Norte, Pernambuco, Bahia, Minas Gerais, Espírito Santo, Rio de Janeiro and the Federal District, as well as the São Paulo Mobile Service.
According to a note from the Brazilian laboratory, the evaluation takes place using “high-resolution mass spectrometry (MS) and the measurement of proteins that cause brain changes related to Alzheimer’s disease.”
The promise is of a less complicated and high-quality exam, capable of excluding Alzheimer’s disease in the face of “other causes of cognitive impairment, such as depression, sleep apnea, vascular dementia and metabolic problems.” It would also be a safer diagnostic option than other tests, as it does not use invasive or radioactive methods on the patient.
In the case of the best known of these, cerebral amyloid PET, it is necessary to perform a lumbar puncture, which is the insertion of a needle into the patient’s back to capture fluid from the spinal cord. Furthermore, the biomarkers in the liquid contain radiation and the test costs R$9,124.
Aurélio Pimenta Dutra, neurologist at Fleury Medicina e Saúde, states that studies on the exam carried out in countries such as Canada and South Korea point to important savings in the Alzheimer’s process. The use of serum tests, according to him, reduces not only the time needed for diagnosis and adequate treatment, but also for investigation and therapy, allowing the selection of individuals who will benefit from a treatment that modifies the evolution of the disease.
If the PrecivityAD2 shows a positive result for Alzheimer’s, it is recommended that a confirmatory test with biomarkers in liquor or amyloid PET be carried out next, as the new test is not yet part of the diagnostic methods accepted in the country. “Considering the current diagnostic criteria, in the face of a clinical picture of cognitive impairment and a positive plasma test, it is recommended to confirm with another study, since plasma tests are not yet in the diagnostic criteria for Alzheimer’s disease”, reinforces Dutra.
The clinical validation of PrecivityAD2 involved two independent cohorts (a set of people with common characteristics) and evaluated a total of 583 patients with cognitive impairment using amyloid PET as the reference standard.
According to the manufacturer’s study, the test achieved 88% accuracy.
Independent research, carried out by Lund University, in Sweden, with four other cohorts and around a thousand patients, would also have highlighted the high precision of the exam, configuring it as an important milestone in the issue of Alzheimer’s.
For doctor Luiz Roberto Ramos, professor at the Department of Preventive Medicine and coordinator of the Center for the Study of Aging at the Federal University of São Paulo (Unifesp), despite still having a high cost and not being covered by the SUS or by health insurance plans, the examination is a positive diagnostic reinforcement. “It makes it simpler to know if someone with cognitive impairment is accumulating beta amyloid without needing PET, and allows us to estimate the [proteína] tau”, says Ramos.
Alzheimer’s in Brazil
Around 1.2 million people in Brazil live with Alzheimer’s disease, according to data from the Ministry of Health. There is still no cure, but early diagnosis allows pharmacological and cognition treatment through individual or group therapy, reducing speed of disease progression.
A healthy diet, treating pre-existing comorbidities (such as hypertension and obesity), practicing physical activity and exercising regularly also contribute to controlling the disease.