06/06/2025  |  Mayo Clinic

https://www.newswise.com/articles/pesquisadores-da-mayo-clinic-validam-exame-de-sangue-para-diagnosticar-alzheimer-em-cl-nicas-ambulatoriais-de-mem-ria 

Newswise — JACKSONVILLE, Florida — Alzheimer's disease, characterized by memory loss, problems with concentration and thinking, and changes in personality and behavior, has a major impact on the lives of patients, their families, and loved ones. With new treatments available for people with early signs of the disease, there is a growing need for accessible, low-cost tests to diagnose Alzheimer's earlier. In a new study, Mayo Clinic researchers confirmed the accuracy of a Food and Drug Administration (FDA)-approved blood test that can be used in outpatient memory clinics to diagnose the disease in patients with varying degrees of cognitive impairment. The findings are published in Alzheimer's and Dementia: The Journal of the Alzheimer's Association.

Traditional methods of measuring the accumulation of toxic proteins in the brain, which indicate Alzheimer's disease, include positron emission tomography (PET) and lumbar punctures. However, these tests can be expensive and invasive. More accessible, noninvasive, and low-cost biomarkers—measurable indicators of a disease—are needed to improve overall diagnostics in clinical settings.

“Our study found that the blood test confirms the diagnosis of Alzheimer's disease with 95% sensitivity and 82% specificity,” says corresponding author Dr. Gregg Day, a neurologist specializing in dementia and a clinical researcher at the Mayo Clinic. “When performed in an outpatient setting, the test has similar accuracy to cerebrospinal fluid biomarkers, with the advantage of being much more convenient and low cost."

The research team says their findings indicate great potential for:

• Better identifying research participants who have brain changes associated with Alzheimer's disease.
• Screening and selecting Alzheimer's patients for participation in clinical trials.
• Assessing how patients respond to therapies during clinical trials.

More than 500 patients being treated for different types of memory problems at the Mayo Clinic Memory Disorders Clinic in Florida participated in the study. The group consisted of patients with early-onset and late-onset cognitive impairment, typical and atypical Alzheimer's disease, Lewy body dementia, and vascular cognitive impairment.

Patients ranged in age from 32 to 89, with an average age of onset of symptoms of 66. In 56% of cases, Alzheimer's disease was determined to be the underlying cause of symptoms. The team also performed serum tests to assess kidney function, which in turn can impact plasma biomarker levels.

Mayo Clinic laboratories analyzed two types of proteins in blood plasma associated with the accumulation of amyloid plaques, a central feature of Alzheimer's disease: Aβ42/40 and p-tau217. The researchers observed that p-tau217 levels were higher in patients with Alzheimer's compared to those without the disease. In addition, they found that higher concentrations of p-tau217 in plasma were also associated with impaired kidney function, a factor that, according to the researchers, should be taken into account when performing blood tests.

Plasma p-tau217 concentrations were positive in 267 of the 509 patients, including 233 of the 246 patients (95%) with cognitive impairment attributed to Alzheimer's disease.

The study was presented at the American Academy of Neurology's Annual Meeting in April.

In a previous study, researchers from the Mayo Clinic laboratories had already demonstrated the usefulness of these blood tests compared to amyloid PET scans in research participants.

Dr. Day says the next steps in this research include evaluating the blood tests in more diverse patient populations and in people with early-stage Alzheimer's who do not yet have cognitive symptoms. In addition, the team also plans to investigate specific disease factors that may impact the accuracy of biomarkers in clinical trials.

Other Mayo Clinic authors include Dr. Yoav Piura, Dr. Christian Lachner, Ph.D. Joshua Bornhorst, Ph.D. Alicia Algeciras Schimnich, and Dr. Neill Graff-Radford. For a complete list of authors, funding, and disclosures, see the article.

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