PET imaging transformed Alzheimer’s research when it enabled scientists to track the spread of Aß pathology in living people. It revealed that amyloid plaques appear decades before symptoms of Alzheimer’s disease emerge. But what about neurofibrillary tangles? With the advent of tau tracers, scientists are now beginning to correlate the two major hallmarks of AD in real time. The results may clarify exactly how AD develops before a patient notices that anything is amiss. Read more.