CHI3L1 and Parkinson disease: However, some studies reported higher CSF CHI3L1 concentrations in AD versus controls,219–222 while no significant differences were reported in other independent analyses.223,224 A meta-analysis compared CSF CHI3L1 in six different cohorts of AD patients and five cohorts of normal controls demonstrating a moderate significant effect size.217,225 For PD, a significant increase of CSF CHI3L1 concentrations was observed in PD patients, after a 2-year follow-up, compared with baseline but not in healthy controls, and was associated to a faster cognitive decline in PD versus healthy controls.226