Detangling the association between traumatic brain injury, mental health, and suicide in active duty service members

Suicide in the military represents a significant and multifaceted problem, with complex and interdependent factors contributing to its occurrence. Disentangling the intricate temporal associations between suicide and its numerous risk factors poses a significant challenge. Of the purported risk factors, traumatic brain injury (TBI) has received special focus, given its unfortunate status as the signature injury in active duty service members who served in Operation Enduring Freedom and Operation Iraqi Freedom. The complex interplay between TBI, its potential effects on mental health, and risk of suicide remains a vexing focus of ongoing investigations and academic inquiry.

In this study, Brenner and colleagues1 present a retrospective cohort analysis of active duty service members in the Department of Defense Substance Use and Psychological Injury Combat Study. This large study includes more than 860 000 active duty service members returning from deployment in Afghanistan or Iraq and is bolstered by uniform access to participant records. Of note, 12.6% of the cohort had documentation of at least 1 TBI, but this likely represents an underestimate, given diagnostic difficulty associated with this injury and limits of electronic medical record review.1 Brenner et al1 compared the onset of new behavioral health conditions over time between a matched sample of active duty service members with and without documented, military-identified TBI. Although the cohort was mostly younger men, the striking findings include marked increases in mental health diagnoses, most notably mood (increased 67.7% in active duty service members with TBI vs 37.5% in those without) and substance use disorders (increased 100% in active duty service members with TBI vs 14.5% in those without). Brenner et al1 found that time to suicide was markedly faster among active duty service members with history of TBI compared with those without a history of TBI (21.3% faster; estimate, 0.787; 95% CI, 0.715-0.866), especially among individuals with new-onset substance use disorder (62.8% faster; estimate, 0.372; 95% CI, 0.322-0.433). This study underscores the burden of suicide and multidimensionality of suicide risk among military personnel and veterans.