CHI3L1 and Alzheimer disease: In this study we wanted to measure classical (Aβ42, t-tau, p-tau) and candidate (Aβ38, Aβ40, sAPPα, sAPPβ, apolipoprotein E, neurogranin, YKL-40 and VILIP-1) AD biomarkers in CSF collected at six time points (08:00; 12:00; 16:00; 20:00, 00:00, 08:00) during 24 h to assess these markers for diurnal variation.