A longitudinal PET study used the florzolotau tracer to show that faster tau accumulation on imaging tracks with more rapid clinical decline in progressive supranuclear palsy (PSP). Patients whose brain tau built up more quickly experienced worse worsening trajectories. The finding positions tau PET not just as a diagnostic imaging marker, but as a potential progression-rate readout that could be useful for stratification in clinical trials. The study’s design ties imaging kinetics to clinical outcomes over time, rather than relying on cross-sectional comparisons. For the neurodegeneration field, the work reinforces the value of quantitative PET tracers when testing therapies where slowing progression is the goal. It also adds to the toolkit of measurable disease progression endpoints in PSP, a condition where clinical heterogeneity can complicate trial design.