A test has been created to detect Alzheimer's before 'knots' form in neurons

BarcelonaScience has found that long before the onset of Alzheimer's symptoms, the brain already has two defining elements of the disease: the formation of neurofibrillary clusters of the Tau protein, which are a kind of tangle that prevents communication between neurons, and the accumulation of plaques, which is considered an unequivocal sign of the disease. Researchers at the University of Pittsburgh School of Medicine in the United States have focused their efforts on the first of these events and have developed a test based on these Tau clusters to anticipate the diagnosis of Alzheimer's by approximately a decade.

The test can detect small amounts of the Tau protein, which tends to accumulate and pollute the cerebrospinal fluid and blood, before these accumulations are visible on brain scan images, the American researchers reported on Monday in the journal Nature Medicine. Neurofibrillary tangles are mainly made up of Tau, which is the protein responsible for the internal structure of neurons and for the correct transmission of molecules. When a brain suffers from Alzheimer's, however, this protein does not perform its function properly and binds to other filaments of the same protein, dismantling the neuronal mechanism.

According to the study's lead author and psychiatrist Thomas Karikari, the test they propose allows for the identification of "the very early stages of the formation of Tau tangles, up to a decade before the accumulations can appear in a brain scan." However, most of the tests tested and marketed to identify Alzheimer's are based on the other element, the accumulation of plaques of beta-amyloid protein, since they are usually detected before the Tau folds. However, the tangles may be a previous step to both elements and be "more defining" because they correlate more with the severity of cognitive decline.

According to the researcher, while the beta-amyloid protein is a kindling that ignites easily, the board is the match. "A large percentage of people who have brain beta-amyloid deposits will never develop dementia. But once the tau buds ignite on a brain scan, it may be too late to put out the fire and their cognitive health can deteriorate rapidly," exemplifies Karikari.

Although imaging techniques to detect tau remain a reliable and accurate predictor of the protein's load in the brain, the utility of the test is limited by access, high cost and low sensitivity of the tests, the researchers say. In this regard, they say that these scans can only capture the signal of neurofibrillary buds when they are abundant in the brain, which is a time when the degree of brain pathology is already pronounced and difficult to reverse. "The trials show that patients with tau buds are more likely to benefit from new treatments than those with a significant degree of brain tau deposits," Karikari simplifies.