Neuropsychological Changes Following Military Service in Iraq

Abstract

SINCE THE 1990-1991 PERSIAN GULF WAR, THE IDEA that the health of military personnel returning from major deployments should be monitored proactively has been established. Major studies are under way on both sides of the Atlantic on the health of personnel deployed to Iraq. The research that has emerged so far on US veterans of Operation Iraqi Freedom indicates that there have indeed been many psychiatric casualties, with high prevalence rates of symptoms of posttraumatic stress disorder (PTSD), depression, and anxiety. Up to 20% of soldiers and marines returning from deployment to Iraq and Afghanistan met criteria for PTSD. Similar findings have been documented by routine screening performed by the US Army. The situation for UK personnel returning from Operation TELIC in the 2003 Iraq War is—with the exception of reservists—rather different, with a prevalence of PTSD (measured using identical measures to the US studies) and depressive symptoms similar to those of nondeployed personnel. These international differences may in part be explained by the nature of deployments, with US personnel on longer tours of duty in more dangerous parts of Iraq. It also may relate to the populations deployed—the deployed US military personnel are younger and have considerably less experience of active deployment than their British counterparts. Whatever the reasons, some of the most significant health effects for returning personnel seem to have been on mental health, and, thus far, there is no evidence of a repeat of the multiple physical symptoms that characterized Persian Gulf War illness. Most studies on military personnel have not been able to study changes in health before and after deployment. The nature of military operations means that making prior ratings of health is logistically difficult. The study by Vasterling and colleagues in this issue of JAMA is a noteworthy exception. The authors measured neuropsychological function in a cohort of military personnel prior to and following deployment to Operation Iraqi Freedom, and compared these findings with those of a cohort of nondeployed soldiers. The authors report that significant neurocognitive changes occurred after deployment, with a worsening of performance on tasks requiring sustained attention, verbal learning, and visual-spatial memory but an improvement in reaction time. Vasterling et al conclude that these results are not explained by the most likely possibilities: head injury, PTSD, and depression. One of the most consistent groups of symptoms reported following the 1991 Persian Gulf War were what might broadly be described as cognitive. Many veterans of that conflict continue to complain of difficulties in memory, word finding, concentration, and other cognitive impairments. This led to speculation that these symptoms were the result of exposure to neurotoxic agents such as organophosphate pesticides and even sarin nerve gas. As a result, a series of neuropsychological studies of Gulf War veterans was undertaken some considerable time after deployment. A review of the results of these studies did not find a consistent pattern of significant deficits, and although certain subgroups (those who reported multiple symptoms and those who selfreported greater exposure to pesticides) had more deficits, again, there was no consistent pattern. Instead, the authors of the review concluded that these deficits were only mild and that “performance on objective tasks of neuropsychological function showed little correspondence to subjective perceptions of cognitive functioning.” Nevertheless, the rationale for the present study by Vasterling et al was to use neuropsychological testing as a means of assessing possible neural dysfunction, but this time to do so before so many years had elapsed. This study is the first of its kind to follow and reassess representative samples of deployed personnel 2 to 3 months following their return home from war. Whether veterans should be concerned about the findings of Vasterling et al depends on the answers to several other questions. First, are the reported effects clinically significant? The authors emphasize that the neuropsychological changes are “mild” and “subtle.” Although data on the dis-