Increased day-of-injury GFAP was associated with a decreased chance of impairment on the QOLIBRI-OS (OR 0.76, 95% CI 0.66–0.88; p < 0.001), SF12v2 MCS (OR 0.71, 95% CI 0.61–0.82; p < 0.001), and SF12v2 PCS (OR 0.79, 95% CI 0.68–0.91; p = 0.002); occurrence of probable anxiety disorder on the GAD-7 (OR 0.80, 95% CI 0.68–0.95; p = 0.010); occurrence of likely depression on the PHQ-9 (OR 0.80, 95% CI 0.68–0.93 per; p = 0.005); and occurrence of likely PTSD on the PCL-5 (OR 0.80, 95% CI 0.66–0.97; p = 0.028). This evidence concerns the gene GFAP and post-traumatic stress disorder.