Context: The effects of war-zone deployment on neuropsychological health remain poorly understood. Neuropsychological performance deficits serve as sensitive measures of neural dysfunction and are often associated with psychosocial and occupational problems. Previous studies have not conducted objective neuropsychological assessments both before and after a major war-zone deployment.
Objective: To examine objective neuropsychological outcomes of Iraq War deployment in a large military cohort.
Design, setting, and participants: The Neurocognition Deployment Health Study, a prospective, cohort-controlled study conducted at military installations. This report centers on 961 male and female active-duty Army soldiers drawn from the larger cohort. Deploying Army soldiers (n = 654) were examined prior to deployment to Iraq (April-December 2003) and shortly after return (within a mean of 73 days [median, 75 days]; January-May 2005) from Iraq deployment. A comparison group of soldiers (n = 307) similar in military characteristics but not deploying overseas during the study was assessed in sessions timed to be as close as possible to the assessment of deployers. Military unit sampling procedures facilitated representation of combat, combat support, and combat service support functions among both deployers and nondeployers.
Main outcome measures: Individually administered, performance-based neuropsychological tasks. Estimates (beta; the unstandardized parameter estimate) for the absolute differences in adjusted mean outcome scores between deployed and nondeployed groups were determined using generalized estimating equations.
Results: Multiple linear regression analyses adjusted for battalion membership revealed that Iraq deployment, compared with nondeployment, was associated with neuropsychological compromise on tasks of sustained attention (beta = 0.11; P<.001), verbal learning (beta = -1.51; P = .003), and visual-spatial memory (beta = -3.82; P<.001). Iraq deployment was also associated with increased negative state affect on measures of confusion (beta = 1.40; P<.001) and tension (beta = 1.24; P<.001). In contrast, deployment was associated with improved simple reaction time (beta = 4.30; P = .003). Deployment effects remained statistically significant after taking into account deployment-related head injury and stress and depression symptoms.
Conclusions: Deployment to Iraq is associated with increased risk of neuropsychological compromise. Findings point to the need to investigate further the impact of deployment on neural functioning. Public health implications include consideration of neuropsychological compromise in health prevention and postdeployment clinical and occupational management.