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PTSD Post-Deployment: Effects of Traumatic Brain Injury and Combat Exposure

The findings in two new studies clarify public health risks of combat and injury.

Neuropsychiatric symptoms in soldiers deployed in Iraq and Afghanistan constitute a looming public health threat, with researchers reporting increased rates of mental disorders, including post-traumatic stress disorder, in returning troops. However, these retrospective and cross-sectional studies used control groups with various limitations. Now, two new studies shed light on combat exposure and traumatic brain injury as risk factors for developing PTSD.

Results have now been reported from the first large-scale prospective study with longitudinal data on rates of PTSD in deployed soldiers (either exposed or not exposed to combat) and in nondeployed soldiers. Soldiers answered questionnaires before deployment and an average of 2.7 years later. Researchers measured PTSD based on two definitions to maximize sensitivity and specificity. Among 47,837 soldiers, rates of new-onset PTSD were significantly higher among combat-exposed soldiers (7.6%–8.7%) than among nondeployed soldiers (2.3%–3.0%); rates among deployed soldiers without combat exposure were significantly lower (1.4%–2.1%) than among nondeployed soldiers. Female sex, being divorced, and a history of problem drinking were also associated with increased PTSD risk in three of the four service branches (overall, PTSD rates did not differ significantly by branch). Deployment did not affect persistence of symptoms among the 2291 participants with baseline PTSD.

Other researchers surveyed 2525 Army soldiers 3 to 4 months after return from deployment regarding occurrence of head injury, and gathered other data on physical symptoms, depression, and PTSD. Of respondents, 4.9% reported head injury with loss of consciousness (a likely proxy for more severe injury), 10.3% reported head injury with altered mental status, and 17.2% reported nonhead injury. Loss of consciousness was associated with increased risk for PTSD (odds ratio, 2.98) and depression (OR, 3.67); altered mental status was associated only with increased PTSD risk (OR, 1.78). Compared with soldiers with other injuries, both head-injury groups had more physical symptoms, which in further analyses were almost entirely mediated by PTSD and depression.

Comment: The first study documents an approximately threefold increase in PTSD risk in combat-exposed soldiers. More important, it suggests that deployment itself does not increase risk for either new PTSD or persisting PTSD symptoms. The second study suggests that, because protective gear is enabling more soldiers to survive head injuries, there are associated increased risks for PTSD and depression, which, in turn, increase physical symptoms and impair general health. This latter finding should alert physicians to avoid labeling expected stress reactions as permanent effects of brain damage; instead, these reactions are likely reversible with treatment.

— Peter Roy-Byrne, MD

Published in Journal Watch Psychiatry January 30, 2008

Citation(s):

Smith TC et al. New onset and persistent symptoms of post-traumatic stress disorder self reported after deployment and combat exposures: Prospective population based US military cohort study. BMJ 2008 Jan 15; [e-pub ahead of print]. (http://dx.doi.org/10.1136/bmj.39430.638241.AE)

Hoge CW et al. Mild traumatic brain injury in U.S. soldiers returning from Iraq. N Engl J Med 2008 Jan 31; 358:453.

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