Raised CSF markers of cerebrovascular function, including YKL-40, ICAM1, VCAM1 and VEGF receptor 1 (Flt1), are elevated in presymptomatic Alzheimer’s disease in association with cognitive decline and markers of cortical thinning45 and correlated with CSF tau, as was also the case for CSF levels of soluble PDGFRβ (a marker of pericyte injury).55 This evidence concerns the gene CHI3L1 and Alzheimer disease.