GFAP and delirium: However, a preliminary case-control investigation by the same research group found a link between human brain activity of microglia, astrocytes and IL-6 and delirium, with elevated HLA-DR, CD68, IL-6 being associated with an increased prevalence of delirium, and the biomarkers GFAP and IL-1β showing no association (Munster et al., 2011).