Scientists continue to search for new methods to diagnose Alzheimer’s disease that are simpler and less invasive than those currently available. In this line, blood markers have already been discovered that can identify patients with this type of dementia or with some pathological characteristic that allows predicting its appearance.
Now, a test developed by a team of neuroscientists led by a researcher at the University of Pittsburgh School of Medicine (USA) can detect a new marker of neurodegeneration due to Alzheimer’s in a blood sample. Specifically, the test detects the biomarker “brain-derived tau” (or BD-tau), outperforming current diagnostic blood tests used to clinically detect dementia-related neurodegeneration.
The study has been published in the journal Brain and is still in its infancy, so the authors hope to confirm the results in future trials, but according to their findings, the aforementioned biological molecule is specific to this pathology and correlates well with biomarkers of Alzheimer’s neurodegeneration in cerebrospinal fluid (CSF).
“The most important utility of blood biomarkers is to improve people’s lives and predict risk in the diagnosis of Alzheimer’s disease”
“Neuroimaging is now necessary to diagnose Alzheimer’s disease,” explains Thomas Karikari, lead author and associate professor of psychiatry at Pitt. “These tests are expensive and take a long time to schedule, and many patients don’t have access to MRI and PET scanners. Accessibility is a major issue,” he adds. “The most important utility of blood biomarkers is to improve people’s lives, improve clinical confidence and risk prediction in the diagnosis of Alzheimer’s disease,” says Karikari.
Current blood diagnostic methods can accurately detect abnormalities in plasma amyloid beta and the phosphorylated form of tau, but experts have difficulty detecting brain-specific markers of neurodegeneration that are unaffected by potentially misleading contaminants occurring elsewhere. of the organism. For example, blood levels of light neurofilaments, a protein marker of nerve cell damage, are elevated in Alzheimer’s, Parkinson’s, and other dementias, making them less useful when trying to differentiate this dementia from other neurodegenerative disorders.
Test that distinguishes Alzheimer’s from other neurodegenerative pathologies
Karikari and his team – which also include scientists from the University of Gothenburg (Sweden) – developed a technique to detect BD-tau by avoiding floating ‘big tau’ proteins produced by cells outside the brain. To do this, they created a special antibody that selectively binds to BD-tau, making it easy to detect in the blood. They validated their assay in more than 600 patient samples from five independent cohorts, including those from individuals whose Alzheimer’s diagnosis was confirmed after death, as well as from patients with memory deficits suggestive of early-stage Alzheimer’s dementia.
The tests showed that the levels of BD-tau detected in blood samples from patients with this dementia by the new assay matched the levels of tau in the CSF and reliably distinguished Alzheimer’s from other neurodegenerative diseases. BD-tau levels also correlated with the severity of amyloid plaques and tau tangles in brain tissue confirmed by brain autopsy analyses.
“A blood test is cheaper, safer and easier to administer, and can improve clinical confidence in the diagnosis of Alzheimer’s and the selection of participants for clinical trials and monitoring of the disease,” says Karikari. The investigator and her team intend to conduct a large-scale clinical validation of BD-tau in blood in a wide range of research groups, including those recruiting participants of various racial and ethnic backgrounds, memory clinics and of the community.
These studies will also include older adults without biological evidence of Alzheimer’s disease, as well as those at different stages of the disease, to determine if the biomarker results can be generalized to people of all backgrounds and, if confirmed results, pave the way for BD-tau to be commercialized for widespread clinical and prognostic use.
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