Repetitive traumatic brain injury, psychological symptoms, and suicide risk in a clinical sample of deployed military personnel.

IMPORTANCE Traumatic brain injury (TBI) is believed to be one factor contributing to rising suicide rates among military personnel and veterans. This study investigated the association of cumulative TBIs with suicide risk in a clinical sample of deployed military personnel referred for a TBI evaluation. OBJECTIVE To determine whether suicide risk is more frequent and heightened among military personnel with multiple lifetime TBIs than among those with no TBIs or a single TBI. DESIGN Patients completed standardized self-report measures of depression, posttraumatic stress disorder (PTSD), and suicidal thoughts and behaviors; clinical interview; and physical examination. Group comparisons of symptom scores according to number of lifetime TBIs were made, and generalized regression analyses were used to determine the association of cumulative TBIs with suicide risk. PARTICIPANTS Patients included 161 military personnel referred for evaluation and treatment of suspected head injury at a military hospital's TBI clinic in Iraq. MAIN OUTCOMES AND MEASURES Behavioral Health Measure depression subscale, PTSD Checklist-Military Version, concussion symptoms, and Suicide Behaviors Questionnaire-Revised. RESULTS Depression, PTSD, and TBI symptom severity significantly increased with the number of TBIs. An increased incidence of lifetime suicidal thoughts or behaviors was associated with the number of TBIs (no TBIs, 0%; single TBI, 6.9%; and multiple TBIs, 21.7%; P = .009), as was suicidal ideation within the past year (0%, 3.4%, and 12.0%, respectively; P = .04). The number of TBIs was associated with greater suicide risk (β [SE] = .214 [.098]; P = .03) when the effects of depression, PTSD, and TBI symptom severity were controlled for. A significant interaction between depression and cumulative TBIs was also found (β  = .580 [.283]; P = .04). CONCLUSIONS AND RELEVANCE Suicide risk is higher among military personnel with more lifetime TBIs, even after controlling for clinical symptom severity. Results suggest that multiple TBIs, which are common among military personnel, may contribute to increased risk for suicide.