We aimed to evaluate whether associations exist between IGF-1 levels and (1) post-injury symptom severity as measured by the Rivermead Post-Concussion Symptoms Questionnaire (RPQ-13), (2) post-injury depression on the Patient Health Questionnaire-9 (PHQ-9), and (3) anxiety as measured by the Generalized Anxiety Disorder-7 (GAD-7) following TBI. The gene discussed is IGF1; the disease is depressive disorder.