Image-Processing Technique Tracks Tau Tangles as Alzheimer's Disease Develops

An international research team has engineered an automated image-analysis technique to expose the pathological progression of Alzheimer's disease, reports Physicsworld . Their study in Science Translational Medicine detailed the application of positron emission tomography (PET) to track the origin and advancement of tau protein as it corresponds to amyloid-beta levels across the brain anatomy of 443 individuals. The investigators initially used magnetic resonance imaging (MRI) to produce a three-dimensional picture of each individual's unique brain structure, with sufficient detail to visualize various brain subregions. They then conducted two PET studies, with the first using a radiotracer called Pittsburgh compound B, which delineates areas where amyloid-beta is concentrated. The second employed flortaucipir that binds to sites with tau-protein tangles, and then the researchers analyzed the structural MRI data to identify the region most susceptible to initial cortical tau buildup in each individual. They brought the two PET images into alignment with the MRI to assess the amyloid-beta and tau protein levels in each brain subregion. The results indicated that cortical tau protein first manifests in the rhinal cortex, regardless of amyloid-beta levels and often before amyloid-beta buildup; then, when certain individuals additionally accrued amyloid-beta throughout the brain, tau was able to exit the rhinal cortex and spread to the temporal neocortex and extratemporal neocortex. Subjects with the highest baseline tau levels in the rhinal cortex exhibited the largest tau proliferation throughout the neocortex.