Tau oligomers are significantly increased in PSP versus control brains. Analysis of PSP brains via Western blot with T22 and Tau-5 showed tau oligomers, while none were detected in control brains (a). Direct ELISA with T22 showed a significant increase in levels of tau oligomers in PSP patient brains compared to control brains (b). Immunofluorescent staining of individual cells with T22, Tau-5, and AT8 corrected for cell size and background fluorescence showed that PSP brain samples had significantly higher levels of tau oligomers, total tau, and phosphorylated tau (c). *p < 0.05; ***p < 0.001.