Association of Time Since Deployment, Combat Intensity, and Posttraumatic Stress Symptoms With Neuropsychological Outcomes Following Iraq War Deployment

Context: Previous research has demonstrated neuropsychological changes following Iraq deployment. It is unknown whether these changes endure without subsequent war-zone exposure or chronic stress symptoms. Objective: To determine the associations of time since deployment, combat intensity, and posttraumatic stress disorder (PTSD) and depression symptoms with longer-term neuropsychological outcomes in war-deployed soldiers. Design: Prospective cohort study involving (1) soldiers assessed at baseline (median, 42 days prior to deployment) and following return from Iraq (median, 404 days after return and 885 days since baseline), and (2) soldiers more recently returned from deployment assessed at baseline (median, 378 days prior to deployment) and following return from Iraq (median, 122 days after return and 854 days since baseline assessment). Setting: Active-duty military installations. Participants: Two hundred sixty-eight male and female regular active-duty soldiers (164 with 1-year follow-up; 104 recently returned). Main Outcome Measures: Neuropsychological performances (verbal learning, visual memory, attention, and reaction time). Results: There was a significant interaction between time and PTSD symptom severity (B=-0.01 [unstandardized], P=.04). Greater PTSD symptoms were associated with poorer attention in soldiers tested at 1-year follow-up (B=0.01, P=.03) but not in recently returned soldiers. At 1-year follow-up, mean adjusted attention error scores increased by 0.10 points for every 10 points on the PTSD scale. Greater combat intensity was associated with more efficient postdeployment reactiontime performances, regardless of time since deployment (B=0.48, P=.004), with mean adjusted reaction efficiency scores increasing by 4.8 points for every 10 points on the combat experiences scale. Neither depression nor contextual variables (alcohol use and deployment head injury) were significantly related to neuropsychological outcomes. Conclusions: In this study of army soldiers deployed to the Iraq war, only PTSD symptoms (among soldiers back from deployment for 1 year) were associated with a neuropsychological deficit (reduced attention). Greater combat intensity was associated with enhanced reaction time, irrespective of time since return.