(A) Representative images of pons sections from PSP patients and age-matched controls immunostained with antibodies specific for tau oligomers (T22, red) and total tau (Tau 5, green). Quantitative analyses of mean fluorescent intensity shows (B) increased levels of tau oligomers [****, t (18) = 7.38, p<0.0001] but not of total tau [C, t(7) = 1.67, p = 0.138] in cerebrovasculature of patients with PSP compared to age-matched controls. Examples of cerebrovascular oligomeric tau deposits are indicated with white arrows. (D) Representative images of brain sections from frontal cortex of DLB patients and age-matched controls immunostained with antibodies specific for tau oligomers (T22, red) and alpha-synuclein (LB509, green). (E) Quantitative analysis of mean fluorescence intensity did not reveal differences in oligomeric tau immunoreactivity in DLB patients compared to age-matched controls (t(9) = 1.289, p = 0.23). (F) Quantitative analysis of mean fluorescence intensity demonstrates an increase in alpha-synuclein abundance in brains of DLB patients compared to controls (*, t(9)=2.486, p = 0.035). For all studies, n=2 brains/group; 10-15 sections from each sample were analyzed for tau oligomers. All PSP and DLB samples were tested and were positive for tau oligomers.