Mild traumatic brain injury and suicide risk among a clinical sample of deployed military personnel: Evidence for a serial mediation model of anger and depression.

Research has demonstrated a robust link between traumatic brain injuries (TBIs) and suicide risk. Yet, few studies have investigated factors that account for this link. Utilizing a clinical sample of deployed military personnel, this study aimed to examine a serial meditation model of anger and depression in the association of mild TBI and suicide risk. A total of 149 military service members referred for evaluation/treatment of a suspected head injury at a military hospital participated in the present study (92.6% male; M = 27.9y). Self-report measures included the Suicidal Behaviors Questionnaire-Revised (SBQ-R), Automated Neuropsychological Assessment Metrics (ANAM) anger and depression subscales, and Behavioral Health Measure-20 depression subscale. A current mild TBI diagnosis was confirmed by a licensed clinical psychologist/physician. Overall, 84.6% (126/149) of participants met diagnostic criteria for a current mild TBI. Bootstrapped serial mediation analyses indicated that the association of mild TBI and suicide risk is serially mediated by anger and depression symptoms (bias-corrected 95% confidence interval [CI] for the indirect effect = 0.044, 0.576). An alternate serial mediation model in which depression symptoms precede anger was not statistically significant (bias-corrected 95% CI for the indirect effect = -0.405, 0.050). Among a clinical sample of military personnel, increased anger and depression statistically mediated the association of mild TBI and suicide risk, and anger appears to precede depression in this pathway. Findings suggest that therapeutically targeting anger may serve to thwart the trajectory to suicide risk among military personnel who experience a mild TBI. Future research should investigate this conjecture within a prospective design to establish temporality.