Study Suggests Traumatic Brain Injury during Most Recent Deployment Strongest Predictor of Post-Deployment PTSD
BACKGROUND:
According to prior reports, approximately 10%-20% of OEF/OIF/OND service members report mild TBI or concussion, and nearly 60% of those report exposure to more than one blast (i.e., IEDs, rocket-propelled grenades, land mines). Whether TBI is a risk factor for PTSD has been difficult to determine because of the prevalence of comorbid conditions, overlapping symptoms, and cross-sectional samples. Using data from the Marine Resiliency Study – a prospective, longitudinal study of infantry Marines – investigators in this study examined whether deployment-related TBI predicts PTSD symptom severity when accounting for combat intensity and pre-deployment characteristics. Specifically, investigators analyzed data from 1,648 active-duty Marine and Navy service members who completed pre-deployment and post-deployment assessments between July 14, 2008 and May 24, 2012. Structured clinical interviews and self-report assessments were administered approximately one month before a 7-month deployment to Iraq or Afghanistan, and again 3 to 6 months after deployment. The primary outcome measure was the total score on the Clinician-Administered PTSD Scale (CAPS) administered 3 months after deployment. Other study measures included: pre-deployment TBI and psychiatric symptoms, combat intensity, general cognitive ability, and demographics.
FINDINGS:
- At the pre-deployment assessment, 57% of service members reported prior TBI; at post-deployment assessment, 20% reported deployment-related TBI.
- Even when accounting for pre-deployment psychiatric symptoms, prior TBI, and combat intensity, TBI sustained during the most recent deployment was the strongest predictor of post-deployment PTSD symptoms. Deployment-related TBI nearly doubled the likelihood of post-deployment PTSD for service members who reported minimal to no PTSD symptoms before deployment.
- The probability of post-deployment PTSD was greatest for service members with severe pre-deployment symptoms, high combat intensity, and deployment-related TBI.
LIMITATIONS:
- Retrospective, self-report measures limit causal inference and reflect potentially inconsistent documentation of in-theater events.
- CAPS threshold scores for partial PTSD and PTSD that were validated in civilians may be conservative for diagnosis in a military population.
IMPLICATIONS:
- Findings suggest that deployment-related TBI may be an important risk factor for PTSD, particularly for individuals with symptoms related to a prior traumatic event.
AUTHOR/FUNDING INFORMATION:
This study was partly supported by HSR&D (SDR 09-128). Drs. Yurgil, Nievergelt, and Baker are part of the VA San Diego Healthcare System; Drs. Vasterling and Litz are part of the VA Boston Healthcare System.
Yurgil K, Barkauskas D, Vasterling J, Nievergelt C, Larson G, Schork N, Litz B, Nash W, and Baker DG for the Marine Resiliency Study Team. Association between Traumatic Brain Injury and Risk of Post-Traumatic Stress Disorder in Active-Duty Marines. JAMA Psychiatry December 11, 2013;Epub ahead of print.
