16 Jan 2023 • "Brain-derived tau: a novel blood-based biomarker for Alzheimer’s disease-type neurodegeneration has been detected by a group of neuroscientists led by a University of Pittsburgh School of Medicine researchers. They developed a test to detect rare biomarkers of Alzheimer's disease neurodegeneration in a blood sample. The biomarker, called brain-derived tau, or BD-tau, outperforms current blood diagnostic tests used to detect Alzheimer's-related neurodegeneration clinically. It is specific to Alzheimer's disease and correlates well with Alzheimer's neurodegeneration biomarkers in the cerebrospinal fluid (CSF). Currently, to diagnose Alzheimer’s disease, clinicians use guidelines set in 2011 by the National Institute on Aging and the Alzheimer’s Association. The guidelines, called the AT(N) Framework, require detection of three distinct components of Alzheimer’s pathology—the presence of amyloid plaques, tau tangles and neurodegeneration in the brain—either by imaging or by analyzing CSF samples. Unfortunately, both approaches suffer from economical and practical limitations, dictating the need for development of convenient and reliable AT(N) biomarkers in blood samples, collection of which is minimally invasive and requires fewer resources. By applying their knowledge of molecular biology and biochemistry of tau proteins in different tissues, such as the brain, Karikari and his team, including scientists at the University of Gothenburg, Sweden, developed a technique to selectively detect BD-tau while avoiding free-floating “big tau” proteins produced by cells outside the brain. To do that, they designed a special antibody that selectively binds to BD-tau, making it easily detectible in the blood. They validated their assay across over 600 patient samples from five independent cohorts, including those from patients whose Alzheimer’s disease diagnosis was confirmed after their deaths, as well as from patients with memory deficiencies indicative of early-stage Alzheimer’s. The tests showed that levels of BD-tau detected in blood samples of Alzheimer’s disease patients using the new assay matched with levels of tau in the CSF and reliably distinguished Alzheimer’s from other neurodegenerative diseases.

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