In the study with post-9/11 veterans, plasma GFAP showed a negative association with post-traumatic stress disorder severity.83 The TRACK-TBI study, which evaluated adults with mild to moderate TBI (GCS 13–15, 36.4% with positive CT scans), found that participants with probable post-traumatic stress disorder (PCL-5 ≥ 33) at 6 months had significantly lower plasma GFAP levels on the day of injury.118 This suggests a potential protective role of GFAP against the development of post-traumatic stress disorder in this population. Here, GFAP is linked to acute stress disorder.