GFAP and depressive symptom measurement: This study contributes to the literature by demonstrating that blood biomarkers of acute brain injury may be negatively associated with mental health sequelae such as depression in patients with TBI and negative initial head CT scan, but future work is necessary to better understand this association.22 Clinicians who have access to day-of-injury peripheral GFAP levels (e.g. emergency department providers) should be aware that lower GFAP does not necessarily mean there will not be long-term psychiatric sequelae from TBI.