Acute gene expression analysis in the ipsilateral cortex confirmed histological data with greater GFAP expression in aged than adult TBI mice, confirming previous findings.45 Interestingly, ageing was associated with an early and persistent increased expression of H2-T23, H2-D1 and Ggta1 genes, which have been previously found elevated after LPS-induced neuroinflammation24,25,50 or human neurodegenerative disease.24 In agreement with previous data,43,51 M/m pan markers CD11b and CD68 were increased by both sTBI and ageing. Here, CD68 is linked to neurodegenerative disease.