Day-of-injury GFAP levels were significantly lower for participants with depression compared with those without depression [median (Q1, Q3) = 149.9 (22.7, 733.8) pg/mL versus 306.9 (85.1, 843.3), P < 0.001] in the overall sample and in subgroups with CT- high pre-injury risk (P < 0.001) and CT- low pre-injury risk (P = 0.036), but not in CT+ high or low pre-injury risk subgroups (see Table 2). Here, GFAP is linked to major depressive disorder.