MAPT and Alzheimer disease: Increased levels of YKL-40 were also positively linked to P-tau levels in non-demented controls (Spearman’s rho = 0.5255, p = 0.006), DLB (Spearman’s rho = 0.3665, p = 0.033) and PD (Spearman’s rho = 0.3346, p = 0.0153) but not AD patients (for distribution see S2B and S2C Fig).