Quantification of YKL-40, tau pathology burden and astrogliosis in different tauopathies. a–o Representative images of YKL-40, tau and GFAP immunoreactivity of controls and the four tauopathies under study. a–e YKL-40 expression pattern. f–j Main tau deposits and aggregates of each condition. k–o Astrogliosis among the tauopathies and controls. Scale bar = 20 μm. p YKL-40 immunoreactivity (objects/μm2) measured in all conditions. q–s Correlation between different markers. Levels of YKL-40 and GFAP correlated positively with tau aggregation. Solid lines indicate the linear regression, and dotted lines indicate 95% CI. RS, Spearman rho coefficient.