CHI3L1 and Alzheimer disease: Therefore, we conducted a comparative analysis of selected proteins related to an inflammatory state in the central nervous system (CNS), such as YKL-40, chemokines—CXCL12 and CX3CL1, with proteins reflecting synaptic damage—Ng, NPTXR, and Aβ 1-42, as well as tau proteins (tau, ptau181) in the MCI and early full-blown AD.