Health symptom trajectories and neurotoxicant exposures in Gulf War veterans: the Ft. Devens cohort

Irritable Bowel Syndrome in Veterans with Gulf War Illness Evaluated at VA's War-Related Illness and Injury Study Center

INTRODUCTION

Excess rates of Gulf War illness (GWI) and irritable bowel syndrome (IBS), two chronic multisymptom illnesses, have long been documented among nearly 700,000 veterans who served in the 1990-1991 Persian Gulf War. We sought to report the prevalence, characteristics, and association of GWI and IBS decades after the war in a clinical cohort of deployed Gulf War veterans (GWVs) who were evaluated at the Department of Veterans Affairs' War Related Illness and Injury Study Center (WRIISC) for unexplained chronic symptoms.

MATERIALS AND METHODS

We analyzed data gathered from clinical intake questionnaires of deployed GWVs who were evaluated at WRIISC clinics between 2008 and 2020. We applied Centers for Disease Control (CDC) criteria to determine the prevalence of severe GWI. IBS was identified using Rome IV diagnostic criteria (current IBS) and veterans' self-reported "history of physician-diagnosed IBS." We examined associations between IBS and GWI using bivariate analyses and multivariable logistic regression.

RESULTS

Among the N = 578 GWVs evaluated by the WRIISC, severe GWI (71.8%), history of physician-diagnosed IBS (50.3%) and current IBS (42.2%) were all highly prevalent. Nearly half of GWVs with severe GWI met Rome criteria for IBS (45.8%), and over half reported a history of physician-diagnosed IBS (56.1%). In multivariable models, severe GWI was significantly associated both with current IBS (adjusted odds ratio (aOR): 1.68, 95% CI: 1.11, 2.54) and with veteran-reported history of physician-diagnosed IBS (aOR: 2.15, 95% CI: 1.43, 2.23). IBS with diarrhea (IBS-D) was the most common subtype among GWVs with current IBS (61.1%). However, IBS-mixed affected a significantly greater proportion of veterans with severe GWI, compared to veterans who did not have severe GWI (P = .03).

CONCLUSIONS

More than 20 years after the Persian Gulf War, our findings indicate a high degree of comorbidity between severe GWI and IBS among deployed GWVs seeking care for unexplained illnesses. Our results suggest GWVs with GWI should be screened for IBS for which evidence-based treatments are available and could potentially reduce symptom burden. Conversely, symptoms of IBS should trigger additional evaluation for non-gastrointestinal symptoms in deployed Gulf War veterans to identify possible GWI and ensure a comprehensive approach to care.

Characterizing 1991 Gulf War women veterans from the Boston Biorepository and Integrative Network for Gulf War Illness: demographics, exposures, neuroimaging and cognitive outcomes

Objective: Gulf War Illness (GWI) is a debilitating multisymptom condition that affects nearly a third of 1990-91 Gulf War (GW) veterans. Symptoms include pain, fatigue, gastrointestinal issues, and cognitive decrements. Our work has shown that GWI rates and potential causes for symptoms vary between men and women veterans. Studies have documented neuropsychological and neuroimaging findings mostly in men or combined sex datasets. Data are lacking for women veterans due to lack of power and repositories of women veteran samples. Methods: We characterized GW women veterans in terms of demographics, exposures, neuropsychological and neuroimaging outcomes from the newly collated Boston, Biorepository and Integrative Network (BBRAIN) for GWI. Results: BBRAIN women veterans are highly educated with an average age of 54 years. 81% met GWI criteria, 25% met criteria for current PTSD, 78% were white, and 81% served in the Army. Exposure to combined acetylcholinesterase inhibitors (AChEi) including skin pesticides, fogs/sprays and/or pyridostigmine bromide (PB) anti-nerve gas pill exposure resulted in slower processing speed on attentional tasks and a trend for executive impairment compared with non-exposed women. Brain imaging outcomes showed lower gray matter volumes and smaller caudate in exposed women. Conclusions: Although subtle and limited findings were present in this group of women veterans, it suggests that continued follow-up of GW women veterans is warranted. Future research should continue to evaluate differences between men and women in GW veteran samples. The BBRAIN women sub-repository is recruiting and these data are available to the research community for studies of women veterans.

Longitudinal Patterns of Multimorbidity in Gulf War Era Veterans With and Without Gulf War Illness

Objectives: To examine whether severe Gulf War illness (SGWI) case status was associated with longitudinal multimorbidity patterns. Methods: Participants were users of the Veteran Health Administration Health Care System drawn from the Gulf War Era Cohort and Biorepository (n = 840). Longitudinal measures of multimorbidity were constructed using (1) electronic health records (Charlson Comorbidity Index; Elixhauser; and Veterans Affairs Frailty Index) from 10/1/1999 to 6/30/2023 and (2) self-reported medical conditions (Deficit Accumulation Index) since the war until the survey date. Accelerated failure time models examined SGWI case status as a predictor of time until threshold level of multimorbidity was reached, adjusted for age and sociodemographic and military characteristics. Results: Models, adjusted for covariates, revealed that (1) relative to the SWGI- group, the SGWI+ group was associated with an accelerated time for reaching each threshold and (2) the relationship between SGWI and each threshold was not moderated by age. Discussion: Findings suggest that veterans with SGWI experienced accelerated aging.

Cognitive decrements in 1991 Gulf War veterans: associations with Gulf War illness and neurotoxicant exposures in the Boston Biorepository, Recruitment, and Integrative Network (BBRAIN) cohorts

BACKGROUND

During deployment, veterans of the 1991 Gulf War (GW) were exposed to multiple war-related toxicants. Roughly a third of these veterans continue to exhibit neurotoxicant induced symptoms of Gulf War Illness (GWI), a multi-faceted condition that includes fatigue, pain and cognitive decrements. When studied empirically, both deployed veterans with exposures and those who meet the criteria for GWI are more likely to show deficits in the area of neuropsychological functioning. Although studies have shown cognitive impairments in small sample sizes, it is necessary to revisit these findings with larger samples and newer cohorts to see if other areas of deficit emerge with more power to detect such differences. A group of researchers and clinicians with expertise in the area of GWI have identified common data elements (CDE) for use in research samples to compare data sets. At the same time, a subgroup of researchers created a new repository to share these cognitive data and biospecimens within the GWI research community.

METHODS

The present study aimed to compare cognitive measures of attention, executive functioning, and verbal memory in a large sample of GWI cases and healthy GW veteran controls using neuropsychological tests recommended in the CDEs. We additionally subdivided samples based on the specific neurotoxicant exposures related to cognitive deficits and compared exposed versus non-exposed veterans regardless of case criteria status. The total sample utilized cognitive testing outcomes from the newly collated Boston, Biorepository, Recruitment, and Integrative Network (BBRAIN) for GWI.

RESULTS

Participants included 411 GW veterans, 312 GWI (cases) and 99 healthy veterans (controls). Veterans with GWI showed significantly poorer attention, executive functioning, learning, and short-and-long term verbal memory than those without GWI. Further, GW veterans with exposures to acetylcholinesterase inhibiting pesticides and nerve gas agents, had worse performance on executive function tasks. Veterans with exposure to oil well fires had worse performance on verbal memory and those with pyridostigmine bromide anti-nerve gas pill exposures had better verbal memory and worse performance on an attention task compared to unexposed veterans.

CONCLUSIONS

This study replicates prior results regarding the utility of the currently recommended CDEs in determining impairments in cognitive functioning in veterans with GWI in a new widely-available repository cohort and provides further evidence of cognitive decrements in GW veterans related to war-related neurotoxicant exposures.

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.

Ocular and inflammatory markers associated with Gulf War illness symptoms

To examine the utility of ocular coherence tomography (OCT) metrics, in conjunction with systemic markers of inflammation, in identifying individuals with Gulf War Illness (GWI) symptoms. Prospective case-control study of 108 Gulf War Era veterans, split into 2 groups based on the presence of GWI symptoms, defined by the Kansas criteria. Information on demographics, deployment history, and co-morbidities were captured. 101 individuals underwent OCT imaging and 105 individuals provided a blood sample which was analyzed for inflammatory cytokines using an enzyme-linked immunosorbent assay-based chemiluminescent assay. The main outcome measure was predictors of GWI symptoms, examined with multivariable forward stepwise logistic regression analysis followed by receiver operating characteristic (ROC) analysis. The mean age of the population was 55 ± 4, 90.7% self-identified as male, 53.3% as White, and 54.3% as Hispanic. A multivariable model that considered demographics and co-morbidities found that a lower inferior temporal ganglion cell layer-inner plexiform layer (GCL‒IPL) thickness, higher temporal nerve fiber layer (NFL) thickness, lower interleukin (IL)-1β levels, higher IL-1α levels, and lower tumor necrosis factor-receptor I levels correlated with GWI symptoms. ROC analysis demonstrated an area under the curve of 0.78 with the best cut-off value for the prediction model having a sensitivity of 83% and specificity of 58%. RNFL and GCL‒IPL measures, namely increased temporal thickness and decreased inferior temporal thickness, respectively, in conjunction with a number of inflammatory cytokines, had a reasonable sensitivity for the diagnosis of GWI symptoms in our population.

Combinations of classical and non-classical voltage dependent potassium channel openers suppress nociceptor discharge and reverse chronic pain signs in a rat model of Gulf War illness

In a companion paper we examined whether combinations of K_v7 channel openers (Retigabine and Diclofenac; RET, DIC) could be effective modifiers of deep tissue nociceptor activity; and whether such combinations could then be optimized for use as safe analgesics for pain-like signs that developed in a rat model of GWI (Gulf War Illness) pain. In the present report, we examined the combinations of Retigabine/Meclofenamate (RET/MEC) and Meclofenamate/Diclofenac (MEC/DIC). Voltage clamp experiments were performed on deep tissue nociceptors isolated from rat DRG (dorsal root ganglion). In voltage clamp studies, a stepped voltage protocol was applied (-55 to -40 mV; V_h=-60 mV; 1500 msec) and K_v7 evoked currents were subsequently isolated by Linopirdine subtraction. MEC greatly enhanced voltage dependent conductance and produced exceptional maximum sustained currents of 6.01 ± 0.26 pA/pF (EC₅₀: 62.2 ± 8.99 μM). Combinations of RET/MEC, and MEC/DIC substantially amplified resting currents at low concentrations. MEC/DIC also greatly improved voltage dependent conductance. In current clamp experiments, a cholinergic challenge test (Oxotremorine-M, 10 μM; OXO), associated with our GWI rat model, produced powerful action potential (AP) bursts (85 APs). Optimized combinations of RET/MEC (5 and 0.5 μM) and MEC/DIC (0.5 and 2.5 μM) significantly reduced AP discharges to 3 and 7 Aps, respectively. Treatment of pain-like ambulatory behavior in our rat model with a RET/MEC combination (5 and 0.5 mg/kg) successfully rescued ambulation deficits, but could not be fully separated from the effect of RET alone. Further development of this approach is recommended.

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.