Soldiers Who Have Intense or Traumatic Combat Experiences Exhibit Evidence of Cognitive Changes

In a study of whether neuropsychological changes occur following deployment to war zones, post-traumatic stress disorder appeared to be associated with attention deficits in soldiers one year after returning from Iraq, according to a report in the September issue of Archives of General Psychiatry, one of the JAMA/Archives journals. In addition, intense combat experiences were associated with faster reaction times regardless of how recently a soldier was deployed.

Previous research has suggested that as soldiers face prolonged stressful and life-threatening situations, changes in their brains direct their cognitive (thinking, learning and memory) resources toward survival, according to background information in the article. For instance, they may respond to dangerous events more quickly while losing the ability to pay attention, learn and remember events not related to combat. “However, it remains unknown whether deployment-related neuropsychological changes persist over time, are associated with stress-related factors (e.g., combat intensity, posttraumatic stress disorder [PTSD] symptoms and depressive reactions) or are better accounted for by demographic and contextual variables,” the authors write.

Brian P. Marx, Ph.D., of Veterans Affairs Boston Healthcare System and Boston University School of Medicine, and colleagues studied 268 male and female regular active-duty soldiers who served between 2003 and 2006. All the soldiers were given neuropsychological tests measuring response time, attention and memory before and after deployment. A group of 164 was assessed both immediately and one year following their return, whereas a second group of 104 returned more recently and were assessed before deployment and then a median (midpoint) of 122 days after returning. The assessments also documented demographic and military information, risk factors for neuropsychological disorders and combat intensity and emotional distress.

“Greater PTSD symptoms were associated with poorer attention in soldiers tested at one-year follow-up but not in recently returned soldiers,” the authors write. “Greater combat intensity was associated with enhanced reaction time, irrespective of time since return.” Neither depression nor risk-related variables such as alcohol use and head injury were associated with changes in neuropsychological functioning.

“Recent findings reveal notably high rates of poor mental health outcomes among U.S. service members upon return from Iraq deployment,” the authors write. “Our findings additionally highlight the neuropsychological consequences of chronic PTSD symptoms. Although neuropsychological changes were not profound and, for reaction time, can be construed as desirable in the short term, their significance lies in the demonstration that psychiatric symptoms often reflect more extensive biological changes, including those affecting brain functioning.”

“A growing literature demonstrates the significant impact of prolonged and repetitive stress on health factors (e.g., immune functioning, cardiovascular disease and other systemic medical illnesses) that can be traced to the biological stress response. Thus, subtle cognitive changes (positive or negative) associated with combat exposure or PTSD may represent a warning sign relevant to long-term health.”

Arch Gen Psychiatry. 2009;66[9]:996-1004.