One group found a significant association between the BDNF 66Met SNP and self-reported depression at 1, but not 6, weeks after mild TBI.28 Conversely, the SNP was found to be advantageous to psychological functioning and quality-of-life outcomes in children after mild TBI.29,30 Lastly, in a separate mild TBI sample of adults, BDNF 66Met was not significantly associated with depression symptoms.31 The role of the BDNF 66Met SNP in emotional outcomes after moderate-severe TBI has not been investigated. Here, BDNF is linked to major depressive disorder.