In people with Alzheimer’s disease, changes in the brain begin many years before the first sign of memory problems. Those changes include the gradual accumulation of beta-amyloid peptides and tau proteins, which form plaques and tangles that are considered hallmarks of the disease. While amyloid plaques have received much attention as an early indicator of disease, until very recently there hadn’t been any way during life to measure the buildup of tau protein in the brain. As a result, much less is known about the timing and distribution of tau tangles and its relationship to memory loss.
Now, in a study published in Science Translational Medicine, an NIH-supported research team has produced some of the first maps showing where tau proteins build up in the brains of people with early Alzheimer’s disease . The new findings suggest that while beta-amyloid remains a reliable early sign of Alzheimer’s disease, tau may be a more informative predictor of a person’s cognitive decline and potential response to treatment.
The study, led by Beau Ances and Matthew Brier of Washington University, St. Louis, set out to explore how the accumulation of tau and beta-amyloid, though linked to different pathological processes, are related clinically in tracking the progression of Alzheimer’s disease. To take a look, they imaged beta-amyloid and used a newly available imaging agent for tau that, when injected into a person’s bloodstream, binds to the protein and makes it visible in positron imaging tomography (PET) scans of the brain.
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