A Pilot Analysis of the Effect of Past Traumatic Events on the Neuroendocrine-Immune System and Behavior in Male Subjects with Gulf War Illness

Background: Gulf War Illness (GWI), a poorly understood illness, is a significant health concern affecting approximately 250,000 veterans who were deployed during the 1990-1991 Gulf War. However, an effective treatment for GWI still remains to be discovered. GWI is often comorbid with Posttraumatic Stress Disorder (PTSD), and due to symptoms that are unexplained by standard clinical diagnosis and the assumptions that veterans must have suffered from some form of battlefield stress, these conditions are difficult to disentangle. The overall effects of past traumatic events on the clinical presentation of GWI have not been evaluated. This pilot study aims to examine the differences in behavioral, immune, and cardiac function profiles between GWI participants with and without self-reported past traumatic events to determine if trauma delineates clinical subtypes of GWI. Method: A total of 21 participant profiles describing behavior, cardiac, cytokine, and endocrine function before, during, and after maximal exercise challenge were obtained from veterans recruited from the Miami Veterans Administration Medical Center. Participants were clustered into two groups via k-means clustering based on scores obtained on the Davidson Trauma Scale (DTS): Intrusiveness, Hyperarousal, and Avoidance/Numbing. Analysis of Variance (ANOVA) was used to examine the subgroup effect on psychological measures (SF36, MFI, Krupps), immune cytokine profiles and autonomic variables (heart rate variability, work). Results: Findings suggest a highly significant difference for age (p \u3c 0.01), with individuals with higher DTS scores being significantly older than those with lower DTS scores. The psychological measure results showed a significant (p \u3c 0.05) between groups main effect for physical and social functioning. Marginally significant differences (p \u3c 0.1) in pain, emotional limits, fatigue and IL-4 blood plasma concentrations at peak exercise were also found. In all cases, those reporting significantly higher DTS scores were found to perform worse on all variables and measures. Conclusions: The results of this pilot study indicate differences in behavior, immune, and cardiac measures suggesting separate phenotypes for individuals with GWI with and without prior trauma