IFNG and Alzheimer disease: to determine the levels of AD-related biomarkers (Aβ42, p-tau, total tau), non-AD-related Aβ isoforms (Aβ38, Aβ40), sAPP isoforms (sAPPα, sAPPβ), proinflammatory cytokines (IL 1β, 2, 4, 5, 8, 10, 12p70, and 13, IFN-γ, MCP-1, TNF-α) and biomarkers of neuronal damage (NFL, MBP) in lumbar and ventricular CSF, and how they correlate,