CHI3L1 and Alzheimer disease: Previous research has shown that high levels of CSF YKL-40 are significantly associated with the accumulation of AD pathologies and increase the risk of AD dementia (Ferrari-Souza et al., 2022; Janelidze et al., 2018; Pelkmans et al., 2024; Vergallo et al., 2020; Warmenhoven et al., 2024).