deployed to the Persian Gulf, the two groups of Gulf War military personnel reported roughly twice the prevalence of symptoms suggestive of fibromyalgia, cognitive dysfunction, depression, alcohol abuse, asthma, posttraumatic stress disorder (PTSD), sexual discomfort, and chronic fatigue.4 In a separate analysis, the prevalence of MCS symptoms was about twice the prevalence in the comparison population (Black et al. 2000). Furthermore, in the main cohort study, which used a standardized instrument for assessing functioning (the Medical Outcome Study’s 36-item questionnaire known as the Short Form-36, or SF-36), Gulf War veterans displayed significantly lower scores on all eight subscales for physical and mental health. The subscales profile aspects of quality of life. The subscales for bodily pain, general health, and vitality showed the greatest absolute differences between deployed and nondeployed veterans. In short, this large, well-controlled study demonstrated that some sets of symptoms were more frequent and quality of life poorer among Gulf War veterans than among nondeployed military controls.

Symptom Clustering

The Iowa study was the first major population-based study to group sets of symptoms into categories suggestive of known syndromes or disorders, such as fibromyalgia or depression. Its finding of considerably higher prevalence of symptom groups suggestive of fibromyalgia, depression, and cognitive dysfunction among Gulf War veterans motivated other researchers to examine, through factor analysis, the potential for a new syndrome that would group and classify veterans’ symptoms. Several years later, the Iowa investigators performed a factor analysis on their cohort (Doebbeling et al. 2000). They identified three symptom factors in deployed veterans—somatic distress, psychologic distress, and panic—but the factors were not exclusive to deployed veterans. Thus, the study did not support the existence of a new syndrome (see Chapter 3 for a discussion of factor analysis).

Exposure-Symptom Relationships

The Iowa study assessed exposure-symptom relationships by asking veterans to report on their exposures in the Gulf War. Researchers found that many of the self-reported exposures were significantly associated with health conditions. For example, symptoms of cognitive dysfunction were found to have been associated with self-reports of exposure to solvents or petrochemicals, smoke or combustion products, lead from fuels, pesticides, ionizing or nonionizing radiation, chemical-warfare agents, use of pyridostigmine bromide (PB), infectious agents, and physical trauma. A similar set of exposures were associated with symptoms of depression or fibromyalgia. The study concluded that no exposure to any single agent was related to the conditions that the authors found to be more prevalent in Gulf War veterans (Iowa Persian Gulf Study Group 1997).

Women’s Health

The Gulf War was among the first wars to see a sizable fraction of women in the military. About 7% of military personnel serving in the Persian Gulf were women (Joseph 1997). The Iowa study was one of the few population-based US studies that investigated the health of

Checklist—Military, the Centers for Disease Control and Prevention Chronic Fatigue Syndrome Questionnaire, the Chalder Fatigue Scale, the American Thoracic Society questionnaire, and the Sickness Impact Profile.


The conditions listed were not diagnosed, because no clinical examinations were performed. Rather, before conducting their telephone survey, researchers grouped sets of symptoms from their symptom checklists into a priori categories of diseases or disorders. After a veteran identified himself or herself as having the requisite set of symptoms, researchers analyzing responses considered the veteran as having symptoms “suggestive” of or consistent with a particular disorder but not as having a formal diagnosis of the disorder.

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