Deployment stressors and a chronic multisymptom illness among Gulf War veterans

Association of deployment characteristics and exposures with persistent ill health among 1990-1991 Gulf War veterans in the VA Million Veteran Program

BACKGROUND

Veterans of the 1990-1991 Gulf War have experienced excess health problems, most prominently the multisymptom condition Gulf War illness (GWI). The Department of Veterans Affairs (VA) Cooperative Studies Program #2006 "Genomics of Gulf War Illness in Veterans" project was established to address important questions concerning pathobiological and genetic aspects of GWI. The current study evaluated patterns of chronic ill health/GWI in the VA Million Veteran Program (MVP) Gulf War veteran cohort in relation to wartime exposures and key features of deployment, 27-30 years after Gulf War service.

METHODS

MVP participants who served in the 1990-1991 Gulf War completed the MVP Gulf War Era Survey in 2018-2020. Survey responses provided detailed information on veterans' health, Gulf War exposures, and deployment time periods and locations. Analyses determined associations of three defined GWI/ill health outcomes with Gulf War deployment characteristics and exposures.

RESULTS

The final cohort included 14,103 veterans; demographic and military characteristics of the sample were similar to the full population of U.S. 1990-1991 Gulf War veterans. Overall, a substantial number of veterans experienced chronic ill health, as indicated by three defined outcomes: 49% reported their health as fair or poor, 31% met Centers for Disease Control and Prevention criteria for severe GWI, and 20% had been diagnosed with GWI by a healthcare provider. Health outcomes varied consistently with veterans' demographic and military characteristics, and with exposures during deployment. All outcomes were most prevalent among youngest veterans (< 50 years), Army and Marine Corps veterans, enlisted personnel (vs. officers), veterans located in Iraq and/or Kuwait for at least 7 days, and veterans who remained in theater from January/February 1991 through the summer of 1991. In multivariable models, GWI/ill health was most strongly associated with three exposures: chemical/biological warfare agents, taking pyridostigmine bromide pills, and use of skin pesticides.

CONCLUSIONS

Results from this large cohort indicate that GWI/chronic ill health continues to affect a large proportion of Gulf War veterans in patterns associated with 1990-1991 Gulf War deployment and exposures. Findings establish a foundation for comprehensive evaluation of genetic factors and deployment exposures in relation to GWI risk and pathobiology.

Prolonged Antibiotic Use in a Preclinical Model of Gulf War Chronic Multisymptom-Illness Causes Renal Fibrosis-like Pathology via Increased micro-RNA 21-Induced PTEN Inhibition That Is Correlated with Low Host Lachnospiraceae Abundance

Gulf War (GW) veterans show gastrointestinal disturbances and gut dysbiosis. Prolonged antibiotic treatments commonly employed in veterans, especially the use of fluoroquinolones and aminoglycosides, have also been associated with dysbiosis. This study investigates the effect of prolonged antibiotic exposure on risks of adverse renal pathology and its association with gut bacterial species abundance in underlying GWI and aims to uncover the molecular mechanisms leading to possible renal dysfunction with aging. Using a GWI mouse model, administration of a prolonged antibiotic regimen involving neomycin and enrofloxacin treatment for 5 months showed an exacerbated renal inflammation with increased NF-κB activation and pro-inflammatory cytokines levels. Involvement of the high mobility group 1 (HMGB1)-mediated receptor for advanced glycation end products (RAGE) activation triggered an inflammatory phenotype and increased transforming growth factor-β (TGF-β) production. Mechanistically, TGF-β- induced microRNA-21 upregulation in the renal tissue leads to decreased phosphatase and tensin homolog (PTEN) expression. The above event led to the activation of protein kinase-B (AKT) signaling, resulting in increased fibronectin production and fibrosis-like pathology. Importantly, the increased miR-21 was associated with low levels of Lachnospiraceae in the host gut which is also a key to heightened HMGB1-mediated inflammation. Overall, though correlative, the study highlights the complex interplay between GWI, host gut dysbiosis, prolonged antibiotics usage, and renal pathology via miR-21/PTEN/AKT signaling.

The effect of disease misclassification on the ability to detect a gene-environment interaction: implications of the specificity of case definitions for research on Gulf War illness

BACKGROUND

Since 1997, research on Gulf War illness (GWI) has predominantly used 3 case definitions-the original Research definition, the CDC definition, and modifications of the Kansas definition-but they have not been compared against an objective standard.

METHODS

All 3 case definitions were measured in the U.S. Military Health Survey by a computer-assisted telephone interview in a random sample (n = 6,497) of the 1991 deployed U.S. military force. The interview asked whether participants had heard nerve agent alarms during the conflict. A random subsample (n = 1,698) provided DNA for genotyping the PON1 Q192R polymorphism.

RESULTS

The CDC and the Modified Kansas definition without exclusions were satisfied by 41.7% and 39.0% of the deployed force, respectively, and were highly overlapping. The Research definition, a subset of the others, was satisfied by 13.6%. The majority of veterans meeting CDC and Modified Kansas endorsed fewer and milder symptoms; whereas, those meeting Research endorsed more symptoms of greater severity. The group meeting Research was more highly enriched with the PON1 192R risk allele than those meeting CDC and Modified Kansas, and Research had twice the power to detect the previously described gene-environment interaction between hearing alarms and RR homozygosity (adjusted relative excess risk due to interaction [aRERI] = 7.69; 95% CI 2.71-19.13) than CDC (aRERI = 2.92; 95% CI 0.96-6.38) or Modified Kansas without exclusions (aRERI = 3.84; 95% CI 1.30-8.52) or with exclusions (aRERI = 3.42; 95% CI 1.20-7.56). The lower power of CDC and Modified Kansas relative to Research was due to greater false-positive disease misclassification from lower diagnostic specificity.

CONCLUSIONS

The original Research case definition had greater statistical power to detect a genetic predisposition to GWI. Its greater specificity favors its use in hypothesis-driven research; whereas, the greater sensitivity of the others favor their use in clinical screening for application of future diagnostic biomarkers and clinical care.

Hormonal changes in veterans with Gulf War Illness

AIMS

Gulf War Illness (GWI) is a multi-system condition of complex etiology and pathophysiology without specific treatment. There is an overlap between the symptoms of GWI and endocrinopathies. This study aimed to identify hormonal alterations in 1990-91 Gulf War (GW) veterans and the relationship between GWI and hormonal dysregulation.

MAIN METHODS

Data from 81 GW veterans (54 with GWI and 27 controls without GWI) was analyzed in a cross-sectional, case-control observational study. Participants completed multiple questionnaires, neuropsychiatric assessments, and a comprehensive set of hormone assays including a glucagon stimulation test (GST) for adult growth hormone deficiency (AGHD) and a high-dose adrenocorticotropic hormone (ACTH) stimulation test for adrenal insufficiency.

KEY FINDINGS

The GWI group had lower quality of life and greater severity of all symptoms compared to controls. Pain intensity and pain-related interference with general activity were also higher in the GWI group. AGHD was observed in 18 of 51 veterans with GWI (35.3 %) and 2 of 26 veterans without GWI (7.7 %) (p = 0.012 for interaction). Veterans with GWI also exhibited reduced insulin-like growth factor 1 (IGF-1) levels and IGF-1 Z-scores compared to controls. One participant with GWI met the criteria for adrenal insufficiency. No significant changes were observed in other hormonal axes.

SIGNIFICANCE

The frequency of AGHD was significantly higher in veterans with GWI compared to controls. Recombinant human growth hormone replacement therapy (GHRT) may become a breakthrough therapeutic option for this subgroup. A large clinical trial is needed to evaluate the efficacy of GHRT in patients with GWI and AGHD.

Association of Gulf War Illness with Characteristics in Deployed vs. Non-Deployed Gulf War Era Veterans in the Cooperative Studies Program 2006/Million Veteran Program 029 Cohort: A Cross-Sectional Analysis

Gulf War Illness (GWI), a chronic multisymptom illness with a complex and uncertain etiology and pathophysiology, is highly prevalent among veterans deployed to the 1990-1991 GW. We examined how GWI phenotypes varied by demographic and military characteristics among GW-era veterans. Data were from the VA's Cooperative Studies Program 2006/Million Veteran Program (MVP) 029 cohort, Genomics of GWI. From June 2018 to March 2019, 109,976 MVP enrollees (out of a total of over 676,000) were contacted to participate in the 1990-1991 GW-era Survey. Of 109,976 eligible participants, 45,169 (41.1%) responded to the 2018-2019 survey, 35,902 respondents met study inclusion criteria, 13,107 deployed to the GW theater. GWI phenotypes were derived from Kansas (KS) and Centers for Disease Control and Prevention (CDC) GWI definitions: (a) KS Symptoms (KS Sym+), (b) KS GWI (met symptom criteria and without exclusionary health conditions) [KS GWI: Sym+/Dx-], (c) CDC GWI and (d) CDC GWI Severe. The prevalence of each phenotype was 67.1% KS Sym+, 21.5% KS Sym+/Dx-, 81.1% CDC GWI, and 18.6% CDC GWI severe. These findings affirm the persistent presence of GWI among GW veterans providing a foundation for further exploration of biological and environmental underpinnings of this condition.

Evaluation of a Gene-Environment Interaction of PON1 and Low-Level Nerve Agent Exposure with Gulf War Illness: A Prevalence Case-Control Study Drawn from the U.S. Military Health Survey's National Population Sample

BACKGROUND

Consensus on the etiology of 1991 Gulf War illness (GWI) has been limited by lack of objective individual-level environmental exposure information and assumed recall bias.

OBJECTIVES

We investigated a prestated hypothesis of the association of GWI with a gene-environment (GxE) interaction of the paraoxonase-1 (PON1) Q192R polymorphism and low-level nerve agent exposure.

METHODS

A prevalence sample of 508 GWI cases and 508 nonpaired controls was drawn from the 8,020 participants in the U.S. Military Health Survey, a representative sample survey of military veterans who served during the Gulf War. The PON1 Q192R genotype was measured by real-time polymerase chain reaction (RT-PCR), and the serum Q and R isoenzyme activity levels were measured with PON1-specific substrates. Low-level nerve agent exposure was estimated by survey questions on having heard nerve agent alarms during deployment.

RESULTS

The GxE interaction of the Q192R genotype and hearing alarms was strongly associated with GWI on both the multiplicative [prevalence odds ratio (POR) of the interaction=3.41; 95% confidence interval (CI): 1.20, 9.72] and additive (synergy index=4.71; 95% CI: 1.82, 12.19) scales, adjusted for measured confounders. The Q192R genotype and the alarms variable were independent (adjusted POR in the controls=1.18; 95% CI: 0.81, 1.73; p=0.35), and the associations of GWI with the number of R alleles and quartiles of Q isoenzyme were monotonic. The adjusted relative excess risk due to interaction (aRERI) was 7.69 (95% CI: 2.71, 19.13). Substituting Q isoenzyme activity for the genotype in the analyses corroborated the findings. Sensitivity analyses suggested that recall bias had forced the estimate of the GxE interaction toward the null and that unmeasured confounding is unlikely to account for the findings. We found a GxE interaction involving the Q-correlated PON1 diazoxonase activity and a weak possible GxE involving the Khamisiyah plume model, but none involving the PON1 R isoenzyme activity, arylesterase activity, paraoxonase activity, butyrylcholinesterase genotypes or enzyme activity, or pyridostigmine.

DISCUSSION

Given gene-environment independence and monotonicity, the unconfounded aRERI>0 supports a mechanistic interaction. Together with the direct evidence of exposure to fallout from bombing of chemical weapon storage facilities and the extensive toxicologic evidence of biochemical protection from organophosphates by the Q isoenzyme, the findings provide strong evidence for an etiologic role of low-level nerve agent in GWI. https://doi.org/10.1289/EHP9009.

Association of Gulf War Illness-Related Symptoms with Military Exposures among 1990-1991 Gulf War Veterans Evaluated at the War-Related Illness and Injury Study Center (WRIISC)

Veterans with difficult-to-diagnose conditions who receive care in the Department of Veterans Affairs (VA) healthcare system can be referred for evaluation at one of three specialty VA War-Related Illness and Injury Study Centers (WRIISC). Veterans of the 1990−1991 Gulf War have long experienced excess rates of chronic symptoms associated with the condition known as Gulf War Illness (GWI), with hundreds evaluated at the WRIISC. Here we provide the first report from a cohort of 608 Gulf War Veterans seen at the WRIISC who completed questionnaires on chronic symptoms (>6 months) consistent with GWI as well as prominent exposures during Gulf War deployment. These included veterans’ reports of hearing chemical alarms/donning Military-Ordered Protective Posture Level 4 (MOPP4) gear, pesticide use, and use of pyridostigmine bromide (PB) pills as prophylaxis against the effects of nerve agents. Overall, veterans in the cohort were highly symptomatic and reported a high degree of exposures. In multivariable models, these exposures were significantly associated with moderate-to-severe chronic symptoms in neurocognitive/mood, fatigue/sleep, and pain domains. Specifically, exposure to pesticides was associated with problems with concentration and memory, problems sleeping, unrefreshing sleep, and joint pain. Use of MOPP4 was associated with light sensitivity and unrefreshing sleep and use of PB was associated with depression. We also evaluated the association of exposures with symptom summary scores based on veterans’ severity of symptoms in four domains and overall. In multivariable modeling, the pain symptom severity score was significantly associated with pesticide use (Odds ratio (OR): 4.13, 95% confidence intervals (CI): 1.78−9.57) and taking PB pills (OR: 2.28, 95% CI: 1.02−5.09), and overall symptom severity was significantly associated with use of PB pills (OR: 2.41, 95% CI: 1.01−5.75). Conclusion: Decades after deployment, Gulf War veterans referred to a VA tertiary evaluation center report a high burden of chronic symptoms, many of which were associated with reported neurotoxicant exposures during the war.

Pyridostigmine bromide, chlorpyrifos, and DEET combined Gulf War exposure insult depresses mitochondrial function in neuroblastoma cells

Gulf War Illness (GWI) is defined by the Centers for Disease Control and Prevention (CDC) as a multi-symptom illness having at least one symptom from two of three factors, which include: fatigue, mood-cognition problems, and musculoskeletal disorders. The cluster of long-term symptoms is unique to military personnel from coalition countries including United States, Australia, and the United Kingdom that served in Operation Desert Storm from 1990 to 1991. Reporting of these symptoms is much lower among soldiers deployed in other parts of the world like Bosnia during the same time period. The exact cause of GWI is unknown, but combined exposure to N,N-diethyl-m-toluamide (DEET), organophosphates like chlorpyrifos (CPF), and pyridostigmine bromide (PB), has been hypothesized as a potential mechanism. Mitochondrial dysfunction is known to occur in most neurodegenerative diseases that share symptoms with GWI and has therefore been implicated in GWI. Although exposure to these and other toxicants continues to be investigated as potential causes of GWI, their combined impact on mitochondrial physiology remains unknown. In this study, the effects of combined GWI toxicant exposure on mitochondrial function were determined in a commonly used and readily available immortalized cell line (N2a), whose higher rate of oxygen consumption resembles that of highly metabolic neurons in vivo. We report that combined exposure containing pesticide CPF 71 μM, insect repellants DEET 78 μM, and antitoxins PB 19 μM, causes profound mitochondrial dysfunction after a 4-h incubation resulting in decreased mitochondrial respiratory states in the absence of proapoptotic signaling, proton leak, or significant increase in reactive oxygen species production.

Associations of Immune Genetic Variability with Gulf War Illness in 1990-1991 Gulf War Veterans from the Gulf War Illness Consortium (GWIC) Multisite Case-Control Study

Gulf War illness (GWI) encompasses a constellation of persistent debilitating symptoms associated with significant changes in central nervous system (CNS) and immune functioning. Currently, there is no validated biomarker for GWI risk susceptibility. Given the impact of immune responses linked to GWI symptomology, genetic variability that causes persistent inflammatory/immune alterations may be key. This Boston University-based Gulf War Illness Consortium (GWIC) study investigated the impact of single nucleotide polymorphisms (SNPs) in variants of immune and pain genetic markers IL1B, IL2, IL6, IL6R, IL10, TNF, TGF, TLR2, TLR4, MD2, MYD88, BDNF, CRP, ICE, COMT and OPRM1 on GWI occurrence in a Caucasian subset of Gulf War (GW) veterans with (cases, n = 170) and without (controls, n = 34) GWI. Logistic regression modeling created a prediction model of GWI risk that associated genetic variability in TGF (rs1800469, p = 0.009), IL6R (rs8192284, p = 0.004) and TLR4 (rs4986791, p = 0.013) with GWI occurrence. This prediction model was specific and sensitive, with a receiver operator characteristic area under the curve of 71.4%. This is the first report of immune genetic variability being predictive of GWI and warrants validation in larger independent cohorts. Future reports will present interactions of these genetic risk factors with other characteristics of GW service.

Brain-Immune Interactions as the Basis of Gulf War Illness: Clinical Assessment and Deployment Profile of 1990-1991 Gulf War Veterans in the Gulf War Illness Consortium (GWIC) Multisite Case-Control Study

The Boston University-based Gulf War Illness Consortium (GWIC) is a multidisciplinary initiative developed to provide detailed understanding of brain and immune alterations that underlie Gulf War illness (GWI), the persistent multisymptom disorder associated with military service in the 1990–1991 Gulf War. The core GWIC case-control clinical study conducted in-depth brain and immune evaluation of 269 Gulf War veterans (223 GWI cases, 46 controls) at three U.S. sites that included clinical assessments, brain imaging, neuropsychological testing, and analyses of a broad range of immune and immunogenetic parameters. GWI cases were similar to controls on most demographic, military, and deployment characteristics although on average were two years younger, with a higher proportion of enlisted personnel vs. officers. Results of physical evaluation and routine clinical lab tests were largely normal, with few differences between GWI cases and healthy controls. However, veterans with GWI scored significantly worse than controls on standardized assessments of general health, pain, fatigue, and sleep quality and had higher rates of diagnosed conditions that included hypertension, respiratory and sinus conditions, gastrointestinal conditions, and current or lifetime depression and post-traumatic stress disorder. Among multiple deployment experiences/exposures reported by veterans, multivariable logistic regression identified just two significant GWI risk factors: extended use of skin pesticides in theater (adjusted OR = 3.25, p = 0.005) and experiencing mild traumatic brain injury during deployment (OR = 7.39, p = 0.009). Gulf War experiences associated with intense stress or trauma (e.g., participation in ground combat) were not associated with GWI. Data and samples from the GWIC project are now stored in a repository for use by GWI researchers. Future reports will present detailed findings on brain structure and function, immune function, and association of neuroimmune measures with characteristics of GWI and Gulf War service.

The association of pre-war medical conditions to Gulf War Illness

AIMS

Gulf War Illness (GWI) remains a significant health concern for many veterans. The relation of pre-war health conditions and symptoms to GWI could aid in developing a more accurate case definition of GWI. The objective of this study was to investigate pre-war predictors of GWI in a population-based sample of Gulf War veterans using two definitions of GWI.

MAIN METHODS

Data come from the 1995-1997 National Health Survey of Persian Gulf War Era Veterans, a survey of a representative sample of deployed and non-deployed US veterans. Using two definitions of GWI (CDC/Kansas and a newly developed 3-domain definition), we conducted a series of multivariable logistic regression analyses to assess the associations of demographic, lifestyle factors, and pre-war medical conditions and symptoms to subsequent GWI.

KEY FINDINGS

All pre-war symptom predictor domains were significantly and positively associated with GWI using a new 3-domain definition with aORs for individual domains ranging from 2.17 (95% CI = 1.99-2.38) for dermatologic conditions to 3.06 (95% CI = 2.78-3.37) for neurological conditions. All symptom predictor domains were associated with significantly increased likelihood of GWI using the CDC/Kansas definition, with aORs ranging from 2.54 (95% CI = 2.31-2.81) for inflammatory conditions to 3.22 (95% CI = 2.94-3.55) for neurological conditions. These estimates were attenuated but remained significant after inclusion of all significant symptom predictor domains.

SIGNIFICANCE

Results from this study suggest that demographic/lifestyle factors and pre-war medical conditions are strong predictors of GWI. Additional research is needed to confirm these findings, and to clarify the unique characteristics of this common, but still poorly understood illness.

Genomics of Gulf War Illness in U.S. Veterans Who Served during the 1990-1991 Persian Gulf War: Methods and Rationale for Veterans Affairs Cooperative Study #2006

Background: Approximately 697,000 members of the U.S. Armed Forces were deployed to the Persian Gulf in support of the 1990–1991 Persian Gulf War (GW). Subsequently, many deployed and some non-deployed veterans developed a chronic multi-symptom illness, now named Gulf War Illness (GWI). This manuscript outlines the methods and rationale for studying the genomics of GWI within the Million Veteran Program (MVP), a VA-based national research program that has linked medical records, surveys, and genomic data, enabling genome-wide association studies (GWASs). Methods: MVP participants who served in the military during the GW era were contacted by mail and invited to participate in the GWI study. A structured health questionnaire, based on a previously tested instrument, was also included in the mailing. Data on deployment locations and exposures, symptoms associated with GWI, clinical diagnoses, personal habits, and health care utilization were collected. Self-reported data will be augmented with chart reviews and structured international classification of disease codes, to classify participants by GWI case status. We will develop a phenotyping algorithm, based on two commonly used case definitions, to determine GWI status, and then conduct a nested case-control GWAS. Genetic variants associated with GWI will be investigated, and gene–gene and gene–environment interactions studied. The genetic overlap of GWI with, and causative mechanisms linking this illness to, other health conditions and the effects of genomic regulatory mechanisms on GWI risk will also be explored. Conclusions: The proposed initial GWAS described in this report will investigate the genomic underpinnings of GWI with a large sample size and state-of-the-art genomic analyses and phenotyping. The data generated will provide a rich and expansive foundation on which to build additional analyses.

Gulf War illness in the Gulf War Era Cohort and Biorepository: The Kansas and Centers for Disease Control definitions

AIMS

This study characterizes Gulf War Illness (GWI) among U.S. veterans who participated in the Gulf War Era Cohort and Biorepository (GWECB).

MAIN METHODS

Mailed questionnaires were collected between 2014 and 2016. Self-reported GWI symptoms, symptom domain criteria, exclusionary diagnoses, and case status were examined based on the originally published Kansas and Centers for Disease Control (CDC) definitions in the GWECB cohort (n = 849 deployed to Gulf and n = 267 non-deployed). Associations among GWI and deployment status, demographic, and military service characteristics were examined using logistic regression.

KEY FINDINGS

Among deployed veterans in our sample, 39.9% met the Kansas criteria and 84.2% met the CDC criteria for GWI. Relative to non-deployed veterans, deployed veterans had a higher odds of meeting four GWI case status-related measures including the Kansas symptom criteria (aOR = 2.05, 95% CI = 1.50, 2.80), Kansas GWI case status (aOR = 1.42, 95% CI = 1.05, 1.93), the CDC GWI case status (aOR = 1.57, 95% CI = 1.07, 2.29) and the CDC severe criteria (aOR = 2.67, 95% CI = 1.79, 3.99). Forty percent met the Kansas exclusionary criteria, with no difference by deployment status. Some symptoms were nearly universally endorsed.

SIGNIFICANCE

This analysis provides evidence of a sustained, multisymptom illness in veterans who deployed to the Persian Gulf War compared to non-deployed Gulf War era veterans nearly 25 years later. Differences in symptoms attributed to GWI by deployment status have diminished since initial reports, suggesting the need to update GWI definitions to account for aging-related conditions and symptoms. This study provides a foundation for future efforts to establish a single GWI case definition and analyses that employ the biorepository.

Sex-Based Differences in Plasma Autoantibodies to Central Nervous System Proteins in Gulf War Veterans versus Healthy and Symptomatic Controls

Veterans from the 1991 Gulf War (GW) have suffered from Gulf War illness (GWI) for nearly 30 years. This illness encompasses multiple body systems, including the central nervous system (CNS). Diagnosis and treatment of GWI is difficult because there has not been an objective diagnostic biomarker. Recently, we reported on a newly developed blood biomarker that discriminates GWI from GW healthy controls, and symptomatic controls with irritable bowel syndrome (IBS) and myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). The present study was designed to compare levels of these biomarkers between men and women with GWI, as well as sex-specific effects in comparison to healthy GW veterans and symptomatic controls (IBS, ME/CFS). The results showed that men and women with GWI differ in 2 of 10 plasma autoantibodies, with men showing significantly elevated levels. Men and women with GWI showed significantly different levels of autoantibodies in 8 of 10 biomarkers to neuronal and glial proteins in plasma relative to controls. In summary, the present study addressed the utility of the use of plasma autoantibodies for CNS proteins to distinguish among both men and women veterans with GWI and other healthy and symptomatic control groups.

Acetylcholinesterase inhibitor exposures as an initiating factor in the development of Gulf War Illness, a chronic neuroimmune disorder in deployed veterans

Gulf War Illness (GWI) is a chronic multi-symptom disorder, characterized by symptoms such as fatigue, pain, cognitive and memory impairment, respiratory, skin and gastrointestinal problems, that is experienced by approximately one-third of 1991 Gulf War veterans. Over the nearly three decades since the end of the war, investigators have worked to elucidate the initiating factors and underlying causes of GWI. A significant portion of this research has indicated a strong correlation between GWI and exposure to a number of different acetycholinesterase inhibitors (AChEIs) in theater, such as sarin and cyclosarin nerve agents, chlorpyrifos and dichlorvos pesticides, and the anti-nerve agent prophylactic pyridostigmine bromide. Through studying these exposures and their relationship to the symptoms presented by ill veterans, it has become increasingly apparent that GWI is the likely result of an underlying neuroimmune disorder. While evidence indicates that AChEIs are a key exposure in the development of GWI, particularly organophosphate AChEIs, the mechanism(s) by which these chemicals instigate illness appears to be related to "off-target", non-cholinergic effects. In this review, we will discuss the role of AChEI exposure in the development and persistence of GWI; in particular, how these chemicals, combined with other exposures, have led to a chronic neuroimmune disorder. This article is part of the special issue entitled 'Acetylcholinesterase Inhibitors: From Bench to Bedside to Battlefield'.

The prevalence of headaches, pain, and other associated symptoms in different Persian Gulf deployment periods and deployment durations

OBJECTIVES

This study aims to assess (1) the difference in the prevalence of headaches, pain, and other associated symptoms between Gulf War I (1990-1991) and Post-Gulf War I (1992-2015) veterans who served as active military personnel in the Persian Gulf and (2) how the durations of deployment may affect the prevalence of those symptoms.

METHODS

With institutional human subject committee approval, veterans who were accepted to the Gulf War Registry at the VA San Diego Healthcare System between July 2013 and June 2015 (N = 367) were included in this retrospective chart review study and grouped according to the Gulf War period they served under or how long they were deployed to the Persian Gulf. Chi-square was used for categorical data analyses and analysis of variance was conducted for continuous outcomes. All analyses were two-tailed, where applicable, with α = 0.05 and Bonferroni for pairwise group comparisons.

RESULTS

Veterans who served during Post-Gulf War I or both Gulf War I and Post-Gulf War I exhibited more pain and neurological symptoms than Gulf War I veterans (p = 0.005, p = 0.003). In addition, veterans who served ⩾12 months reported more overall pain symptoms and analgesic use than those who served less time (p < 0.001, p = 0.024).

CONCLUSION

The findings suggest that the length of deployment and Persian Gulf deployment period may play a role in acquiring headaches, pain, and other associated symptoms with increased analgesic consumption.

The Relationship Between Traumatic Brain Injury and Rates of Chronic Symptomatic Illness in 202 Gulf War Veterans

Introduction

Although not a "signature injury" of Operation Desert Shield/Desert Storm (i.e., Gulf War, GW), some GW veterans have a history traumatic brain injury (TBI). For example, a previous study found that 12.2% of the GW veterans from the Fort Devens Cohort Study had self-reported TBIs. The present study sought to build upon this finding by examining the relationship between TBI and chronic symptomatic illness in a different sample of GW veterans.

Materials and Methods

Participants were 202 GW veterans recruited from 2014 to 2018 at the San Francisco Veterans Affairs Medical Center as part of a VA-funded study on the effects of predicted exposure to low levels of sarin and cyclosarin on brain structure and function. The Ohio State University TBI identification method was used to determine lifetime history of TBI. The Kansas Gulf War Military History and Health Questionnaire was used to assess symptoms and to determine cases of Kansas Gulf War Illness (GWI) and Centers for Disease Control and Prevention (CDC) Chronic Multisymptom Illness (CMI).

Results

Nearly half (47%) the sample had a history of TBI, but only 7% of the TBIs were sustained in injuries that occurred during the GW. Most of the TBIs were sustained in injuries that occurred prior to (73%) or after (34%) the GW. History of TBI was not associated with higher rates of symptomatic illness when it was narrowly defined (i.e., Kansas GWI cases or cases of severe CMI). History of TBI was only associated with higher rates of symptomatic illness when it is broadly defined (i.e., CDC CMI or mild-moderate CMI). There was suggestive evidence that veterans who sustained TBIs during the GW (only seven in the present sample) have poorer functional outcomes compared with GW veterans with non-GW related TBIs.

Conclusions

While TBIs were uncommon during the GW, many GW veterans sustained TBIs prior or after the GW. Because TBI and GWI/CMI share some overlapping symptoms, history of TBI may appear to be associated with increased rates of chronic symptomatic illness in GW veterans if chronic symptomatic illness is defined broadly (i.e., CDC CMI or mild-moderate CMI). History of pre-GW TBI did not affect the veterans' response to exposures/experiences from the GW; however, there was suggestive evidence that veterans who sustained TBIs during the GW may have poorer functional outcomes that GW veterans without TBI or even GW veterans with non-GW-related TBIs. Future, better powered studies with randomly and systematically select participants from the larger population of GW veterans will need to confirm this finding.

The Association Between Toxic Exposures and Chronic Multisymptom Illness in Veterans of the Wars of Iraq and Afghanistan

OBJECTIVE

The purpose of this study was to determine if post-9/11 veterans deployed to the Iraq and Afghanistan conflicts experienced toxic exposures and whether they are related to symptoms of chronic multisymptom illness (CMI).

METHODS

Data from 224 post-9/11 veterans who self-reported exposure to hazards in theater were analyzed using hierarchical regression.

RESULTS

Of the sample, 97.2% endorsed experiencing one or more potentially toxic exposure. In a regression model, toxic exposures and CMI symptoms were significantly associated above and beyond covariates. Follow-up analyses revealed that pesticide exposures, but not smoke inhalation was associated with CMI symptoms.

CONCLUSIONS

These findings suggest that toxic exposures were common among military personnel deployed to the most recent conflicts, and appear to be associated with CMI symptoms. Additional research on the impact of toxic exposures on returning Iraq and Afghanistan Veterans' health is needed.

Meta-analysis of self-reported health symptoms in 1990-1991 Gulf War and Gulf War-era veterans

OBJECTIVES

Across diverse groups of Gulf War (GW) veterans, reports of musculoskeletal pain, cognitive dysfunction, unexplained fatigue, chronic diarrhoea, rashes and respiratory problems are common. GW illness is a condition resulting from GW service in veterans who report a combination of these symptoms. This study integrated the GW literature using meta-analytical methods to characterise the most frequently reported symptoms occurring among veterans who deployed to the 1990-1991 GW and to better understand the magnitude of ill health among GW-deployed veterans compared with non-deployed GW-era veterans.

DESIGN

Meta-analysis.

METHODS

Literature databases were searched for peer-reviewed studies published from January 1990 to May 2017 reporting health symptom frequencies in GW-deployed veterans and GW-era control veterans. Self-reported health symptom data were extracted from 21 published studies. A binomial-normal meta-analytical model was used to determine pooled prevalence of individual symptoms in GW-deployed veterans and GW-era control veterans and to calculate combined ORs of health symptoms comparing GW-deployed veterans and GW-era control veterans.

RESULTS

GW-deployed veterans had higher odds of reporting all 56 analysed symptoms compared with GW-era controls. Odds of reporting irritability (OR 3.21, 95% CI 2.28 to 4.52), feeling detached (OR 3.59, 95% CI 1.83 to 7.03), muscle weakness (OR 3.19, 95% CI 2.73 to 3.74), diarrhoea (OR 3.24, 95% CI 2.51 to 4.17) and rash (OR 3.18, 95% CI 2.47 to 4.09) were more than three times higher among GW-deployed veterans compared with GW-era controls.

CONCLUSIONS

The higher odds of reporting mood-cognition, fatigue, musculoskeletal, gastrointestinal and dermatological symptoms among GW-deployed veterans compared with GW-era controls indicates these symptoms are important when assessing GW veteran health status.

Recent research on Gulf War illness and other health problems in veterans of the 1991 Gulf War: Effects of toxicant exposures during deployment

Veterans of Operation Desert Storm/Desert Shield - the 1991 Gulf War (GW) - are a unique population who returned from theater with multiple health complaints and disorders. Studies in the U.S. and elsewhere have consistently concluded that approximately 25-32% of this population suffers from a disorder characterized by symptoms that vary somewhat among individuals and include fatigue, headaches, cognitive dysfunction, musculoskeletal pain, and respiratory, gastrointestinal and dermatologic complaints. Gulf War illness (GWI) is the term used to describe this disorder. In addition, brain cancer occurs at increased rates in subgroups of GW veterans, as do neuropsychological and brain imaging abnormalities. Chemical exposures have become the focus of etiologic GWI research because nervous system symptoms are prominent and many neurotoxicants were present in theater, including organophosphates (OPs), carbamates, and other pesticides; sarin/cyclosarin nerve agents, and pyridostigmine bromide (PB) medications used as prophylaxis against chemical warfare attacks. Psychiatric etiologies have been ruled out. This paper reviews the recent literature on the health of 1991 GW veterans, focusing particularly on the central nervous system and on effects of toxicant exposures. In addition, it emphasizes research published since 2008, following on an exhaustive review that was published in that year that summarizes the prior literature (RACGWI, 2008). We conclude that exposure to pesticides and/or to PB are causally associated with GWI and the neurological dysfunction in GW veterans. Exposure to sarin and cyclosarin and to oil well fire emissions are also associated with neurologically based health effects, though their contribution to development of the disorder known as GWI is less clear. Gene-environment interactions are likely to have contributed to development of GWI in deployed veterans. The health consequences of chemical exposures in the GW and other conflicts have been called "toxic wounds" by veterans. This type of injury requires further study and concentrated treatment research efforts that may also benefit other occupational groups with similar exposure-related illnesses.

Butyrylcholinesterase genotype and enzyme activity in relation to Gulf War illness: preliminary evidence of gene-exposure interaction from a case-control study of 1991 Gulf War veterans

BACKGROUND

Epidemiologic studies have implicated wartime exposures to acetylcholinesterase (AChE)-inhibiting chemicals as etiologic factors in Gulf War illness (GWI), the multisymptom condition linked to military service in the 1991 Gulf War. It is unclear, however, why some veterans developed GWI while others with similar exposures did not. Genetic variants of the enzyme butyrylcholinesterase (BChE) differ in their capacity for metabolizing AChE-inhibiting chemicals, and may confer differences in biological responses to these compounds. The current study assessed BChE enzyme activity and BChE genotype in 1991 Gulf War veterans to evaluate possible association of this enzyme with GWI.

METHODS

This case-control study evaluated a population-based sample of 304 Gulf War veterans (144 GWI cases, meeting Kansas GWI criteria, and 160 controls). BChE enzyme activity levels and genotype were compared, overall, in GWI cases and controls. Potential differences in risk associated with cholinergic-related exposures in theater were explored using stratified analyses to compare associations between GWI and exposures in BChE genetic and enzyme activity subgroups.

RESULTS

Overall, GWI cases and controls did not differ by mean BChE enzyme activity level or by BChE genotype. However, for the subgroup of Gulf War veterans with less common, generally less active, BChE genotypes (K/K, U/AK, U/A, A/F, AK/F), the association of wartime use of pyridostigmine bromide (PB) with GWI (OR=40.00, p=0.0005) was significantly greater than for veterans with the more common U/U and U/K genotypes (OR=2.68, p=0.0001).

CONCLUSIONS

Study results provide preliminary evidence that military personnel with certain BChE genotypes who used PB during the 1991 Gulf War may have been at particularly high risk for developing GWI. Genetic differences in response to wartime exposures are potentially important factors in GWI etiology and should be further evaluated in conjunction with exposure effects.

Coenzyme Q10 benefits symptoms in Gulf War veterans: results of a randomized double-blind study

We sought to assess whether coenzyme Q10 (CoQ10) benefits the chronic multisymptom problems that affect one-quarter to one-third of 1990-1 Gulf War veterans, using a randomized, double-blind, placebo-controlled study. Participants were 46 veterans meeting Kansas and Centers for Disease Control criteria for Gulf War illness. Intervention was PharmaNord (Denmark) CoQ10 100 mg per day (Q100), 300 mg per day (Q300), or an identical-appearing placebo for 3.5 ± 0.5 months. General self-rated health (GSRH), the primary outcome, differed across randomization arms at baseline, and sex significantly predicted GSRH change, compelling adjustment for baseline GSRH and prompting sex-stratified analysis. GSRH showed no significant benefit in the combined-sex sample. Among males (85% of participants), Q100 significantly benefited GSRH versus placebo and versus Q300, providing emphasis on Q100. Physical function (summary performance score, SPS) improved on Q100 versus placebo. A rise in CoQ10 approached significance as a predictor of improvement in GSRH and significantly predicted SPS improvement. Among 20 symptoms each present in half or more of the enrolled veterans, direction-of-difference on Q100 versus placebo was favorable for all except sleep problems; sign test 19:1, p=0.00004) with several symptoms individually significant. Significance for these symptoms despite the small sample underscores large effect sizes, and an apparent relation of key outcomes to CoQ10 change increases prospects for causality. In conclusion, Q100 conferred benefit to physical function and symptoms in veterans with Gulf War illness. Examination in a larger sample is warranted, and findings from this study can inform the conduct of a larger trial.

An assessment of survey measures used across key epidemiologic studies of United States Gulf War I Era veterans

Over the past two decades, 12 large epidemiologic studies and 2 registries have focused on U.S. veterans of the 1990-1991 Gulf War Era. We conducted a review of these studies' research tools to identify existing gaps and overlaps of efforts to date, and to advance development of the next generation of Gulf War Era survey tools. Overall, we found that many of the studies used similar instruments. Questions regarding exposures were more similar across studies than other domains, while neurocognitive and psychological tools were the most variable. Many studies focused on self-reported survey results, with a range of validation practices. However, physical exams, biomedical assessments, and specimen storage were not common. This review suggests that while research may be able to pool data from past surveys, future surveys need to consider how their design can yield data comparable with previous surveys. Additionally, data that incorporate recent technologies in specimen and genetic analyses would greatly enhance such survey data. When combined with existing data on deployment-related exposures and post-deployment health conditions, longitudinal follow-up of existing studies within this collaborative framework could represent an important step toward improving the health of veterans.

Complex factors in the etiology of Gulf War illness: wartime exposures and risk factors in veteran subgroups

BACKGROUND

At least one-fourth of U.S. veterans who served in the 1990-1991 Gulf War are affected by the chronic symptomatic illness known as Gulf War illness (GWI). Clear determination of the causes of GWI has been hindered by many factors, including limitations in how epidemiologic studies have assessed the impact of the complex deployment environment on veterans' health.

OBJECTIVE

We sought to address GWI etiologic questions by evaluating the association of symptomatic illness with characteristics of veterans' deployment.

METHODS

We compared veteran-reported wartime experiences in a population-based sample of 304 Gulf War veterans: 144 cases who met preestablished criteria for GWI and 160 controls. Veteran subgroups and confounding among deployment variables were considered in the analyses.

RESULTS

Deployment experiences and the prevalence of GWI differed significantly by veterans' location in theater. Among personnel who were in Iraq or Kuwait, where all battles took place, GWI was most strongly associated with using pyridostigmine bromide pills [odds ratio (OR) = 3.5; 95% confidence interval (CI): 1.7, 7.4] and being within 1 mile of an exploding SCUD missile (OR = 3.1; 95% CI: 1.5, 6.1). For veterans who remained in support areas, GWI was significantly associated only with personal pesticide use, with increased prevalence (OR = 12.7; 95% CI: 2.6, 61.5) in the relatively small subgroup that wore pesticide-treated uniforms, nearly all of whom also used skin pesticides. Combat service was not significantly associated with GWI.

CONCLUSIONS

Findings support a role for a limited number of wartime exposures in the etiology of GWI, which differed in importance with the deployment milieu in which veterans served.

HADStress screen for posttraumatic stress: replication in ethiopian refugees

Purpose was to assess whether a 4-symptom somatic screen, shown to correlate with current post-traumatic stress symptoms in 1 refugee group, could function as a screening instrument in another group of refugees. Sample consisted of 512 community-dwelling refugees from Ethiopia. Data collection included demography, types of torture and nontorture trauma experienced a decade earlier in Africa, and current posttraumatic stress symptoms. Somatic symptoms included headaches (H), appetite change (A), dizziness and faintness (D), and sleep problems (S), added with equal weighting into the HADStress Screen, ranging from 0 to 4. Results showed that age, gender, torture, and other trauma experiences from a decade ago, and current posttraumatic stress symptoms predicted current somatic symptoms on univariate analyses. On a negative binomial regression model, current posttraumatic stress symptoms, male gender, and number of torture types predicted a high HADStress score. Post hoc tests supported cut-off levels at 3 and at 4 symptoms. Conclusion is that the HADStress Screen can serve as an efficient, nonthreatening screen for posttraumatic stress symptoms among refugees.

Perspectives on fatigue from the study of chronic fatigue syndrome and related conditions

Fatigue is a symptom whose causes are protean and whose phenotype includes physical, mood, and behavioral components. Chronic fatigue syndrome (CFS) is an illness that has strong biological underpinnings and no definite etiology. Diagnostic criteria established by the Centers for Disease Control and Prevention have helped classify CFS as an overlap of mood, behavioral, and biological components. These include the presence of fatigue for more than 6 months associated with a diminution of functional activity and somatic symptoms, and pain not attributable to a specific diagnosis or disease. Four of the following criteria need to be present: sore throat, impaired memory or cognition, unrefreshing sleep, postexertional fatigue, tender glands, aching stiff muscles, joint pain, and headaches. Many researchers have observed that CFS shares features in common with other somatic syndromes, including irritable bowel syndrome, fibromyalgia, and temporomandibular joint dysfunction. Correlations between inflammation and infection, augmented sensory processing, abnormalities of neurotransmitters, nerve growth factors, low levels of serotonin and norepinephrine, abnormalities of homeostasis of the stress system, and autonomic dysfunction may be hallmarks of CFS. The relative contributions of each of these abnormalities to the profound fatigue associated with CFS need to be explored further to better evaluate and treat the syndrome.

The symmetry rule: a seven-year study of symptoms and explanatory labels among Gulf War veterans

Noticing medical symptoms can cause one to search for explanatory labels such as "ate bad food" or even "exposed to anthrax," and perhaps these labels may cause new symptom reports. The present study examined whether there is empirical support for this symptom-label "symmetry rule." We interviewed veterans (N= 362) from the Gulf War Registry in 1995 and 2002 about their medical symptoms and about their exposure to war-related hazards and stressors. Health symptom reports were strongly correlated between the two time periods and showed relatively stable mean levels, whereas recall of war-related exposures was notably unstable. Veterans starting with fewer medical symptoms recalled fewer war-related exposures seven years later. Initial recollection of chemical and biological warfare exposure (but not other exposures) longitudinally predicted novel medical symptoms. The findings generally support the symmetry rule hypotheses, although the evidence for the label to symptom link was less strong. The findings account for some variability in symptoms and exposure recall over time, but they do not, on their own, account for the Gulf War veterans' elevated number of unexplained medical symptoms.

Gulf War syndrome: an emerging threat or a piece of history?

‘Gulf War syndrome’ is a phrase coined after the 1991 Gulf War to group together disparate, unexplained health symptoms in Gulf veterans. This paper examines the many hypotheses that have been put forward about the origins of the concept and gives an overview of the studies that have attempted to explain the lasting health effects associated with Gulf service. Our review finds that although in the UK there has not yet been evidence of a new Gulf War syndrome as a result of the current conflicts in Iraq and Afghanistan, there is a rise in post-conflict psychiatric disorders now being reported in the USA. We postulate that after conflicts military personnel will always face some form of post-conflict syndrome and the nature of the threats experienced is likely to dictate the form the syndrome might take. We also postulate that media reporting is likely to have influenced and to continue unhelpfully to influence the health of service personnel.

Repeated stress in combination with pyridostigmine Part II: changes in cerebral gene expression

Organophosphates (OP) represent a potential threat in terrorism or during military conflicts. Due to its faculty to protect cholinesterase (ChE) activity against irreversible inactivation by OP, pyridostigmine bromide (PB) was used as a prophylaxis treatment during the first Persian Gulf War. To explain dysfunctions reported by Gulf War Veterans (GWV), it was suggested a potentiation of the operational stress effects by PB given to soldiers. Our companion paper (see part 1 in the same journal issue) describes that PB treatment administered in repeated stress conditions results in long-term perturbations of learning and social behaviour. The present paper examines, in adult male Wistar rats, consequences of the association of repeated stress and PB treatment on gene expression in hypothalamus and hippocampus. PB treatment (1.5 mg/kg/day) was orally administered 30 min before each stress session to inhibit 40% of blood ChE as recommended by NATO. 10 days of stress alone induce a decrease in hypothalamic Il-1alpha expression. Treatment with PB alone increases mineralocorticoid receptor expression in hypothalamus which means that PB may thus modify stress perception by animals. Stressed-PB animals showed increase in hippocampal expression of BDNF, TrkB and CamKIIalpha, three genes implicated in memory development. As a supplement to previous studies showing behavioural and biochemical effects of the association of stress with PB, our data reveal that behavioural effects of this association may be linked with genomic changes in hippocampus. Mechanisms underlying these modifications and their link with memory disturbances reported by GWV remain to be further determined.

Acetylcholinesterase inhibitors and Gulf War illnesses

Increasing evidence suggests excess illness in Persian Gulf War veterans (GWV) can be explained in part by exposure of GWV to organophosphate and carbamate acetylcholinesterase inhibitors (AChEis), including pyridostigmine bromide (PB), pesticides, and nerve agents. Evidence germane to the relation of AChEis to illness in GWV was assessed. Many epidemiological studies reported a link between AChEi exposure and chronic symptoms in GWV. The link is buttressed by a dose-response relation of PB pill number to chronic symptoms in GWV and by a relation between avidity of AChEi clearance and illness, based on genotypes, concentrations, and activity levels of enzymes that detoxify AChEis. Triangulating evidence derives from studies linking occupational exposure to AChEis to chronic health symptoms that mirror those of ill GWV. Illness is again linked to lower activity of AChEi detoxifying enzymes and genotypes conferring less-avid AChEi detoxification. AChEi exposure satisfies Hill's presumptive criteria for causality, suggesting this exposure may be causally linked to excess health problems in GWV.

The long-term hospitalization experience following military service in the 1991 Gulf War among veterans remaining on active duty, 1994-2004

BACKGROUND

Despite more than a decade of extensive, international efforts to characterize and understand the increased symptom and illness-reporting among veterans of the 1991 Gulf War, concern over possible long-term health effects related to this deployment continue. The purpose of this study was to describe the long-term hospitalization experience of the subset of U.S. Gulf War veterans still on active duty between 1994 and 2004.

METHODS

Gulf War veterans on active duty rosters as of October 1, 1994, were identified (n = 211 642) and compared with veterans who had separated from military service and then assessed for attrition at three-year intervals during a 10-year follow-up period, examining demographic and military service characteristics, Gulf War exposure variables, and hospitalization data. Cox proportional hazard modeling was used to evaluate independent predictors of all-cause hospitalization among those still on active duty and to estimate cumulative probability of hospitalization, 1994-2004, by service branch.

RESULTS

Members of our 1994 active duty cohort were more likely to be officers, somewhat older, and married compared with those who had separated from the military after serving in the 1991 Gulf War. Selected war-related exposures or experiences did not appear to influence separation with the exception of in-theater presence during the brief ground combat phase. Overall the top three diagnostic categories for hospitalizations were musculo-skeletal, injury and poisoning, and digestive disorders. Diseases of the circulatory system and symptoms, signs, and ill-defined conditions increased proportionately over time. In-theater hospitalization was the only significant independent predictor of long-term hospitalization risk among selected war-related exposures or experiences examined. The cumulative probability of hospitalization was highest for Army and lowest for Marines.

CONCLUSION

Our results were generally consistent with a previous hospitalization study of US Gulf War veterans for the period August 1991 to July 1999. Although lack of a comparison group for our study limits interpretation of overall findings, intra-cohort analyses showed no significant associations between long-term hospitalization and war-related exposures or experiences, with the exception of in-theater hospitalization, within our active duty subset of 1991 Gulf War veterans.

Latency and Exposure-Health Associations in Gulf War Veterans with Early Fatigue Onsets: A Case-control Study

PURPOSE

To see if self-reported exposures were associated with health in early-onset Gulf War illnesses (GWIs) cases and healthy Gulf War veteran controls.

METHODS

Forty-nine cases and 44 controls completed questionnaires about wartime exposures and symptoms experienced. Odds ratios were calculated using 2 x 2 tables and logistic regression. The incubation curve of fatigue onsets in cases was drawn to highlight exposure/health associations using Sartwell's method and tested with the Shapiro-Wilk test. The incubation period was defined as the time from arrival in the Persian Gulf to fatigue onset.

RESULTS

The incubation curve was right skewed and lognormally distributed (p = 0.48; p > 0.05 indicates lognormality), suggesting an association between a wartime exposure and fatigue. Exposure to oil fire smoke, pesticides, contaminated food or water, dead animals, scud missile attacks, dead bodies, prisoners of war, artillery or small arms fire, and chemical suits was significantly associated with GWIs. Pyridostigmine bromide (PB) was the only continuous exposure significantly associated with GWIs. The odds of having GWIs increased by 1.3% for every PB pill taken (95% confidence interval 1.001-1.02). There were significant trends toward worse health with greater intake of PB.

CONCLUSIONS

These analyses suggest that wartime exposures, including exposure to PB, are associated with fatigue.

Gulf War Illness: lessons from medically unexplained symptoms

Service in the Persian Gulf in 1991 is associated with increased reporting of symptoms and distress in a proportion of those who served there. Yet despite clear evidence of an increase in symptom burden and a decrease in well being, exhaustive clinical and laboratory based scientific research has failed to document many reproducible biomedical abnormalities in this group. Likewise, there has been no evidence of an increase in disease related mortality. Formal psychiatric disorders are twice as common in Gulf War veterans, as might be expected in the aftermath of any conflict, but this too is insufficient to explain the ill-health observed. Many service personnel who returned unwell believe that they have Gulf War Syndrome, and that their ill-health is due to exposures that they encountered in theatre. Research on multiple exposures to date has not generated a plausible aetiological mechanism for veterans' ill-health. Even if medical research has failed to provide a satisfactory explanation, it remains the case that many of those affected continue to be unwell and disabled some 15 years after returning from combat. For this reason, it is time that more attention is given to developing effective interventions to relieve their ill-health and distress. In this review we discuss the importance of the wider social context, individual illness beliefs and attributions and go on to outline a model of continuing ill-health in Gulf veterans. The review concludes with some suggestions for future research priorities, in particular the need for further qualitative studies to further our understanding of the illness, in order that better treatments may be developed.

Pain in veterans of the Gulf War of 1991: a systematic review

Background

Veterans of the Persian Gulf War of 1991 have reported a range of adverse health symptoms. This systematic review aims to identify all studies that have compared the prevalence of symptoms of pain in veterans of the Gulf War to that in a non-Gulf military comparison group, and to determine whether Gulf War veterans are at increased risk of reporting pain.

Methods

Studies published between January 1990 and May 2004 were identified by searching a large number of electronic databases. Reference lists and websites were also searched and key researchers were contacted. Studies were included if they reported the prevalence of any symptom or condition that included the word "pain" in Gulf War veterans and in a comparison group of non-Gulf veterans. 2401 abstracts were independently reviewed by two authors.

Results

Twenty studies fulfilled the inclusion criteria. Five main sites of pain were identified (muscle, joint, chest/heart, back and abdominal pain) and separate meta-analyses were performed to summarise the results related to each site. A greater proportion of Gulf veterans reported symptoms at each site of pain when compared to a non-Gulf military group. Gulf deployment was most strongly associated with abdominal pain, with Gulf veterans being more than three times more likely to report such pain than a comparison group (OR 3.23; 95%CI 2.31–4.51). Statistical heterogeneity between study estimates was significant, probably due to variation in measured periods of prevalence and symptom measurement methods.

Conclusion

A higher proportion of veterans of the Persian Gulf War of 1991 reported symptoms of pain than military comparison groups. This is consistent with previously demonstrated increased reporting of more general symptoms (fatigue, multiple chemical sensitivity, post traumatic stress disorder) in these veterans compared with non-Gulf military groups. However, the primary studies were heterogeneous and varied greatly in quality.

Effects of combined, multiple stressors on pyridostigmine-induced acute toxicity in rats

A number of studies have evaluated the possibility that stress-induced changes in blood-brain barrier permeability enhanced the central effects of the carbamate acetylcholinesterase inhibitor, pyridostigmine. We previously found relatively little evidence of stress-induced changes in the acute toxicity of pyridostigmine in rats using a variety of restraint, forced running and forced swimming stress conditions. In this study, we evaluated the effects of sequential pre-exposure to multiple stressors on the acute toxicity of pyridostigmine. Rats (n = 8 per treatment group) were either un-stressed or stressed by restraint (60 min), forced running (60 min, 15 m/min, 6 degrees incline) and forced swimming (15 min), and then given either vehicle (saline, 1 ml/kg, po) or pyridostigmine (30 mg/kg, po) immediately after the final stressor. Functional signs of cholinergic toxicity (involuntary movements, autonomic dysfunction) were recorded at 0.5, 1 and 2 h after dosing. Body temperature was measured both before stress and 2 h after dosing. Rats were sacrificed immediately after 2-h functional observations to collect tissues (whole blood, diaphragm, frontal cortex, hippocampus and cerebellum) for measurement of cholinesterase activity. Stressed rats treated with pyridostigmine exhibited higher lethality (2/8) compared to unstressed rats given pyridostigmine (0/8). Pyridostigmine elicited classical signs of cholinergic toxicity, but the rats that died did not show increased cholinergic signs and no significant differences in cholinergic signs were noted between treatment groups. Cholinesterase activity was significantly inhibited in blood (47-50%) and diaphragm (80%) following pyridostigmine exposure regardless of stress conditions. Slight but significant inhibition (11-15%) of cerebellar cholinesterase activity was observed following pyridostigmine exposure, but inhibition was not influenced by stress. We conclude that while acute lethality from pyridostigmine may be increased by combined, multiple stressors, increased lethality does not appear due to enhanced cholinergic toxicity or via increased cholinesterase inhibition in either central or peripheral tissues.

Toxicological assessments of Gulf War veterans

Concerns about unexplained illnesses among veterans of the 1991 Gulf War appeared soon after that conflict ended. Many environmental causes have been suggested, including possible exposure to depleted uranium munitions, vaccines and other drugs used to protect troops, deliberate or accidental exposure to chemical warfare agents and pesticides and smoke from oil-well fires. To help resolve these issues, US and UK governments have sought independent expert scientific advice from prestigious, independent scientific and public health experts, including the US National Academies of Science and the UK Royal Society and Medical Research Council. Their authoritative and independent scientific and medical reviews shed light on a wide range of Gulf War environmental hazards. However, they have added little to our understanding of Gulf War veterans' illnesses, because identified health effects have been previously well characterized, primarily in the occupational health literature. This effort has not identified any new health effects or unique syndromes associated with the evaluated environmental hazards. Nor do their findings provide an explanation for significant amounts of illnesses among veterans of the 1991 Gulf War. Nevertheless, these independent and highly credible scientific reviews have proven to be an effective means for evaluating potential health effects from deployment-related environmental hazards.

Why people believe they were exposed to biological or chemical warfare: a survey of Gulf War veterans

The study sought to understand better how people come to believe they have been exposed to biological and chemical warfare. We conducted telephone interviews with 1,009 American veterans (65% response rate) deployed and not deployed to the Gulf War, a conflict during which there were credible threats that such warfare could be used. Only 6% of non-Gulf War veterans reported exposure to biological or chemical warfare, but most of Gulf War veterans reported exposure (64%). The majority of these were unsure whether the exposure was chemical or biological in nature. The most commonly reported exposure indicators were receiving an alert from the military and having physical symptoms. Veterans who were certain of the type of exposure (biological or chemical) were more likely to recall having been told by the military and to recall physical symptoms. Future communications with soldiers and the general public about biological and chemical warfare may need to emphasize the uncertain nature of such risk information. Evaluations of exposure diagnostic technologies should take into account the problem of people initially believing, but not later discounting, false positive results.

Chronic multisymptom illness complex in Gulf War I veterans 10 years later

Prior research has demonstrated that shortly after the 1991 Gulf War (Gulf War I), chronic multisymptom illness (CMI) was more common among deployed veterans than among nondeployed veterans. The aims of the current study were to determine the prevalence of CMI among deployed and nondeployed veterans 10 years after Gulf War I, compare the distribution of comorbid conditions, and identify prewar factors associated with CMI. Cross-sectional data collected from 1,061 deployed veterans and 1,128 nondeployed veterans examined between 1999 and 2001 were analyzed. CMI prevalence was 28.9% among deployed veterans and 15.8% among nondeployed veterans (odds ratio = 2.16, 95% confidence interval: 1.61, 2.90). Deployed and nondeployed veterans with CMI had similarly poorer quality-of-life measures and higher prevalences of symptom-based medical conditions, metabolic syndrome, and psychiatric disorders. Diagnoses of prewar anxiety disorders (not related to post-traumatic stress disorder) and depression were associated with CMI among both deployed and nondeployed veterans. Nicotine dependence and veteran-reported physician-diagnosed infectious mononucleosis were associated with CMI among deployed veterans, and migraine headaches and gastritis were associated with CMI among nondeployed veterans. CMI continues to be substantially more prevalent among deployed veterans than among nondeployed veterans 10 years after Gulf War I, but it manifests similarly in both groups. It is likely to be a common, persistent problem among veterans returning from the current Gulf War.

Biomedical models of fibromyalgia

PURPOSE

Fibromyalgia (FM) and chronic widespread pain (CWP) are common, but the etiology of these disorders remains poorly understood. A large body of data indicates a neurobiological basis for these disorders, but this information has not been effectively transmitted to many medical professionals.

METHODS

Contemporary data on the epidemiologic characteristics of FM and CWP are reviewed, and evidence for a neurobiological basis for these disorders is presented. In addition, possible predisposing, triggering, and maintaining factors for the development of these disorders are discussed.

RESULTS

Approximately 10% of the population have CWP, and approximately 4% have FM. The tender point criteria for FM have resulted in the common misconception among health care professionals that this spectrum of disorders is limited to women with high degrees of psychological distress. A hallmark of FM is the presence of non-nociceptive, central pain. There is evidence of centrally augmented pain processing, which can be detected both with sensory testing and by more objective measures (e.g., evoked potentials, functional neuroimaging).

DISCUSSION

An appreciation of the neurobiological basis for these disorders, and an understanding of some of the abnormalities of pain processing present in patients with FM, will hopefully provide greater understanding of these patients. It may also serve to decrease the level of frustration and improve the care experience of both chronic pain patients and physicians.

Gulf War Syndrome: A Toxic Exposure? A Systematic Review

Using the strength-of-conclusion scheme enumerated in Box 2, based on two class II studies, there is probably a causal link between deployment to the Persian Gulf theater of operation and the development of the poorly defined multisymptom illness known as GWS (level B). Based on class IV studies, there is insufficient evidence to determine if exposure to toxins encountered during the Persian Gulf war caused GWS (level U). A major limitation of the literature regarding the GWS is the reliance on self-reporting to measure exposure to putative causal toxins. Although objective measures of toxin exposure in GWV generally is unavailable, modeling techniques to estimate exposure levels to low-level nerve agents and smoke from oil well fires have been developed. It would be useful to determine if exposure levels determined by these techniques are associated with GWS. The lack of a clear case definition GWS also hampers research. Some go even further, claiming that the absence of such a definition renders the condition illegitimate. Although an objective marker to GWS would be useful for studies, the absence of such a marker does not make the syndrome any less legitimate. in essence, GWS merely is a convenient descriptive term that describes a phenomenon: GWV reporting suffering from medically unexplained health-related symptoms. In this sense, it shares much with the other medically unexplained syndromes encountered in practice. The real debate surrounding medically unexplained conditions is not whether or not they exist, but defining their cause. In this regard, investigators fall into two camps. One camp insists that the conditions are caused by a yet-to-be-discovered medical problem, rejecting out of hand the possibility of a psychologic origin. The other camp insists the conditions are fundamentally psychogenic rejecting the possibility of an undiscovered medical condition. The evidence shows, however, that the conditions exists, the suffering is real, and the causes are unknown.