CHI3L1 and Alzheimer disease: Considering that the pathological mechanisms of neuroinflammation in AD have significant commonalities with other neurodegenerative diseases, and although our current findings may indicate the prospect and potential of YKL-40 being one of the valid candidate biomarkers for AD, its applicability in the differential diagnostic contexts of AD and in monitoring the natural course of AD requires further exploration and additional studies with larger sample sizes to be clarified and validated.