CHI3L1 and Alzheimer disease: It has been shown that microglial activation can trigger neurotoxic reactive astrocytes by secretion of cytokines (Liddelow et al. 2017) and a correlation between YKL-40 and sTREM2 has also been found in Alzheimer’s disease (Heslegrave et al. 2016), normal pressure hydrocephalus (Yang et al. 2023), and prion disease (Diaz-Lucena et al. 2021).