Although previous animal models have suggested a reduction in neurogenesis post-trauma (Dranovsky and Hen, 2006) and an induction in neuronal proliferation post-TBI (Kwon et al., 2011; Gao and Chen, 2013), our investigation of the immature neuronal marker doublecortin in the DG, a hippocampal subfield where postnatal neurogenesis is known to occur, revealed no significant effect of PTSD, mTBI or their combination. The gene discussed is DCX; the disease is concussion.