Psychological differences between veterans with and without Gulf War unexplained symptoms

Objective: The objective of this study was to assess measures of psychological and neurobehavioral functioning to determine their association with unexplained symptoms in Gulf War veterans. Methods: An epidemiological survey focusing on exposures and symptoms was mailed to a random sample of Gulf War veterans from Oregon and southwestern Washington. Volunteers were recruited from survey respondents who agreed to undergo a thorough medical examination and psychological and neurobehavioral assessment. Persistent symptoms with no medical explanation associated with service in the Persian Gulf leg, fatigue, muscle pain, and memory deficits) that began during or after the war qualified respondents as cases. The 241 veterans with unexplained symptoms were classified as case subjects, and the 113 veterans without symptoms were classified as control subjects. All veterans completed a battery of computerized assessment tests consisting of 12 psychosocial and 6 neurobehavioral tests. Differences between case and control subjects on neurobehavioral and psychological variables were assessed with univariate and multivariate statistical comparisons. Results: Case subjects differed substantially and consistently from control subjects on diverse psychological tests in the direction of increased distress and psychiatric symptoms. Case subjects had small but statistically significant deficits relative to control subjects on some neurobehavioral tests of memory, attention, and response speed. A logistic regression model consisting of four psychological variables but no neurobehavioral variables classified case and control subjects with 86% accuracy. Conclusions: Our results revealed that Gulf War veterans who report symptoms associated with that conflict differed on multiple psychological measures in the direction of increased distress and performed more poorly on neurobehavioral measures when compared with control subjects who did not report symptoms. This suggests that psychological differences have a prominent role in investigation of possible explanations of Gulf War symptoms.