New blood test diagnoses Alzheimer's disease decades before symptoms manifest. Digest
Alzheimer’s disease is a neurodegenerative disorder characterized by progressive memory loss, cognitive decline, and behavioral changes. Roughly 50 million people have Alzheimer’s disease worldwide. Researchers have developed a blood test that measures phospho-tau217 (p-tau217), a type of tau protein, and may be useful in diagnosing Alzheimer’s disease as early as 20 years before symptoms manifest.
Tau is a protein that clumps together and forms tangles inside neurons in the brains of people with Alzheimer’s disease. When tau tangles form, the system for transporting mitochondria, lipids, and cellular metabolites is disrupted. As a result, cellular energy is reduced, and new synapse formation is halted, resulting in impaired memory, a hallmark of Alzheimer’s disease. Typically, the presence of tau tangles is determined during autopsy, but it can be observed via PET imaging studies in living persons.
The study involved more than 1,400 people from three cross-sectional cohorts. Some of the participants were cognitively impaired, while others were not. The three cohorts provided data from clinical, neuropathological, imaging, cerebrospinal fluid, blood-based biomarker, and genetic assessments.
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The authors of the study found that the p-tau217 blood test distinguished the presence of Alzheimer’s disease from other neurodegenerative diseases better than currently used biomarkers and equally as well as imaging studies. The test identified early signs of Alzheimer’s disease in people who were genetically predisposed to the condition as much as 20 years before the onset of symptoms. These findings suggest that a simple blood test could accurately diagnose Alzheimer’s disease early in its pathology, potentially providing strategies to delay or prevent the disease.