Effect of basal ganglia injury on central dopamine activity in Gulf War syndrome: correlation of proton magnetic resonance spectroscopy and plasma homovanillic acid levels

Pathophysiological basis and promise of experimental therapies for Gulf War Illness, a chronic neuropsychiatric syndrome in veterans

This article describes the pathophysiology and potential treatments for Gulf War Illness (GWI), which is a chronic neuropsychiatric illness linked to a combination of chemical exposures experienced by service personnel during the first Gulf War in 1991. However, there is currently no effective treatment for veterans with GWI. The article focuses on the current status and efficacy of existing therapeutic interventions in preclinical models of GWI, as well as potential perspectives of promising therapies. GWI stems from changes in brain and peripheral systems in veterans, leading to neurocognitive deficits, as well as physiological and psychological effects resulting from multifaceted changes such as neuroinflammation, oxidative stress, and neuronal damage. Aging not only renders veterans more susceptible to GWI symptoms, but also attenuates their immune capabilities and response to therapies. A variety of experimental models are being used to investigate the pathophysiology and develop therapies that have the ability to alleviate devastating symptoms. Over two dozen therapeutic interventions targeting neuroinflammation, mitochondrial dysfunction, neuronal injury, and neurogenesis are being tested, including agents such as curcumin, curcumin nanoparticles, monosodium luminol, melatonin, resveratrol, fluoxetine, rolipram, oleoylethanolamide, ketamine, levetiracetam, nicotinamide riboside, minocycline, pyridazine derivatives, and neurosteroids. Preclinical outcomes show that some agents have promise, including curcumin, resveratrol, and ketamine, which are being tested in clinical trials in GWI veterans. Neuroprotectants and other compounds such as monosodium luminol, melatonin, levetiracetam, oleoylethanolamide, and nicotinamide riboside appear promising for future clinical trials. Neurosteroids have been shown to have neuroprotective and disease-modifying properties, which makes them a promising medicine for GWI. Therefore, accelerated clinical studies are urgently needed to evaluate and launch an effective therapy for veterans displaying GWI.

Long-term changes in neuroimaging markers, cognitive function and psychiatric symptoms in an experimental model of Gulf War Illness

AIMS

Gulf War Illness (GWI) is a multi-symptom disease with debilitating cognitive and emotional impairments in veterans. GWI, like epilepsy, is caused by chemical neurotoxicity and manifests from disturbances in neuronal excitability. However, the mechanisms underlying such devastating neurological and psychiatric symptoms remain unclear. Here we investigated the long-term changes in neural behavior and brain structural abnormalities in a rat model of GWI. GWI is linked to exposure to GWI-related organophosphate chemicals (pyridostigmine bromide or PB and insecticide DEET, permethrin) during the stressful Gulf war.

METHODS

To mimic GWI, we generated an experimental GWI prototype in rats by daily exposure to GWI-related chemicals with restraint stress (GWIR-CS) for 4 weeks. Changes in MRI scan and cognitive function were assessed at 5- and 10- months post-exposure.

KEY FINDINGS

In MRI scans, rats displayed significant increases in lateral ventricle T2 relaxation times at both 5- and 10-months after GWIR-CS, indicating alterations in the cerebrospinal fluid (CSF) density. Furthermore, at 10 months, there were significant decreases in the volumes of the hippocampus and thalamus and an increase in the lateral ventricle volume. At both time points, they exhibited impairments in multiple neurobehavioral tests, confirming substantial deficits in memory and mood function. GWI-CS rats also displayed aggressive behavior and a marked decrease in social interaction and forced swimming, indicating depression.

CONCLUSIONS

These results confirm that chronic GWIR-CS exposure led to cognitive and psychiatric symptoms with concurrent neuroimaging abnormalities in CSF, with morphological neural lesions, demonstrating the role of divergent etiological mechanisms in GWI and its comorbidities.

Moderate, intermittent voluntary exercise in a model of Gulf War Illness improves cognitive and mood function with alleviation of activated microglia and astrocytes, and enhanced neurogenesis in the hippocampus

Persistent cognitive and mood impairments in Gulf War Illness (GWI) are associated with chronic neuroinflammation, typified by hypertrophied astrocytes, activated microglia, and increased proinflammatory mediators in the brain. Using a rat model, we investigated whether a simple lifestyle change such as moderate voluntary physical exercise would improve cognitive and mood function in GWI. Because veterans with GWI exhibit fatigue and post-exertional malaise, we employed an intermittent voluntary running exercise (RE) regimen, which prevented exercise-induced stress. The GWI rats were provided access to running wheels three days per week for 13 weeks, commencing ten weeks after the exposure to GWI-related chemicals and stress (GWI-RE group). Groups of age-matched sedentary GWI rats (GWI-SED group) and naïve rats were maintained parallelly. Interrogation of rats with behavioral tests after the 13-week RE regimen revealed improved hippocampus-dependent object location memory and pattern separation function and reduced anxiety-like behavior in the GWI-RE group compared to the GWI-SED group. Moreover, 13 weeks of RE in GWI rats significantly reversed activated microglia with short and less ramified processes into non-inflammatory/antiinflammatory microglia with highly ramified processes and reduced the hypertrophy of astrocytes. Moreover, the production of new neurons in the hippocampus was enhanced when examined eight weeks after the commencement of RE. Notably, increased neurogenesis continued even after the cessation of RE. Collectively, the results suggest that even a moderate, intermittent physical exercise has the promise to improve brain function in veterans with GWI in association with suppression of neuroinflammation and enhancement of hippocampal neurogenesis.

Melatonin improves brain function in a model of chronic Gulf War Illness with modulation of oxidative stress, NLRP3 inflammasomes, and BDNF-ERK-CREB pathway in the hippocampus

Persistent cognitive and mood dysfunction is the primary CNS symptom in veterans afflicted with Gulf War Illness (GWI). This study investigated the efficacy of melatonin (MEL) for improving cognitive and mood function with antioxidant, antiinflammatory, and pro-cognitive effects in a rat model of chronic GWI. Six months after exposure to GWI-related chemicals and stress, rats were treated with vehicle or MEL (5, 10, 20, 40, and 80 mg/kg) for eight weeks. Behavioral tests revealed cognitive and mood dysfunction in GWI rats receiving vehicle, which were associated with elevated oxidative stress, reduced NRF2, catalase and mitochondrial complex proteins, astrocyte hypertrophy, activated microglia with NLRP3 inflammasomes, elevated proinflammatory cytokines, waned neurogenesis, and synapse loss in the hippocampus. MEL at 10 mg/kg alleviated simple and associative recognition memory dysfunction and anhedonia, along with reduced oxidative stress, enhanced glutathione and complex III, and reduced NLRP3 inflammasomes, IL-18, TNF-α, and IFN-γ. MEL at 20 mg/kg also normalized NRF2 and catalase and increased microglial ramification. MEL at 40 mg/kg, in addition, reduced astrocyte hypertrophy, activated microglia, NF-kB-NLRP3-caspase-1 signaling, IL-1β, MCP-1, and MIP-1α. Moreover, MEL at 80 mg/kg activated the BDNF-ERK-CREB signaling pathway, enhanced neurogenesis and diminished synapse loss in the hippocampus, and improved a more complex hippocampus-dependent cognitive function. Thus, MEL therapy is efficacious for improving cognitive and mood function in a rat model of chronic GWI, and MEL's effect was dose-dependent. The study provides the first evidence of MEL's promise for alleviating neuroinflammation and cognitive and mood impairments in veterans with chronic GWI.

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A low dose of Melatonin alleviated recognition memory dysfunction and anhedonia in a model of chronic GWI.

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A moderate dose of Melatonin improved more complex cognitive function in a model of chronic GWI.

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Melatonin treatment reduced oxidative stress and enhanced mitochondrial complex proteins in the GWI brain.

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Melatonin inhibited NLRP3 inflammasomes and proinflammatory cytokines in the GWI brain.

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Melatonin activated the BDNF-ERK-CREB signaling pathway and enhanced neurogenesis in the GWI brain.

Cause-specific mortality risks among U.S. veterans: 25 years after their service in the 1990-1991 gulf war

PURPOSE

There is concern about adverse health effects related to military service in the 1990-1991 Gulf War. This study assessed cause-specific mortality risks among Veterans who served in the war.

METHODS

The mortality of 621,244 veterans deployed to the Gulf War was compared to that of 745,704 Veterans who served during the war but were not deployed to the Gulf Theater. Cause-specific mortality of both deployed and nondeployed was also compared to that of the US general population.

RESULTS

There was no increased risk of disease-specific mortality among deployed Veterans compared to nondeployed. Deployed Veterans did have an increased risk of motor vehicle deaths compared to nondeployed Veterans, (hazard ratio, 1.12, 95% confidence interval, 1.04-1.21). Cause-specific mortality of both deployed and non-deployed Veterans was less than that of the US population. When stratified by gender, only female Veterans, both deployed and nondeployed, had increased risks of suicide compared to the female US population (standardized mortality ratio, 1.40; 95% confidence interval, 1.13-1.71 and standardized mortality ratio, 1.22; 95% confidence interval, 1.05-1.40, respectively).

CONCLUSION

There was no increased risk of disease mortality among Veterans of the 1990-1991 Gulf War. Both deployed and nondeployed female Veterans had increased risks of suicide compared to US female population.

Gulf War Illness: Mechanisms Underlying Brain Dysfunction and Promising Therapeutic Strategies

Gulf War Illness (GWI), a chronic multisymptom health problem, afflicts ~30% of veterans served in the first GW. Impaired brain function is among the most significant symptoms of GWI, which is typified by persistent cognitive and mood impairments, concentration problems, headaches, chronic fatigue, and musculoskeletal pain. This review aims to discuss findings from animal prototypes and veterans with GWI on mechanisms underlying its pathophysiology and emerging therapeutic strategies for alleviating brain dysfunction in GWI. Animal model studies have linked brain impairments to incessantly elevated oxidative stress, chronic inflammation, inhibitory interneuron loss, altered lipid metabolism and peroxisomes, mitochondrial dysfunction, modified expression of genes relevant to cognitive function, and waned hippocampal neurogenesis. Furthermore, the involvement of systemic alterations such as the increased intensity of reactive oxygen species and proinflammatory cytokines in the blood, transformed gut microbiome, and activation of the adaptive immune response have received consideration. Investigations in veterans have suggested that brain dysfunction in GWI is linked to chronic activation of the executive control network, impaired functional connectivity, altered blood flow, persistent inflammation, and changes in miRNA levels. Lack of protective alleles from Class II HLA genes, the altered concentration of phospholipid species and proinflammatory factors in the circulating blood have also been suggested as other aiding factors. While some drugs or combination therapies have shown promise for alleviating symptoms in clinical trials, larger double-blind, placebo-controlled trials are needed to validate such findings. Based on improvements seen in animal models of GWI, several antioxidants and anti-inflammatory compounds are currently being tested in clinical trials. However, reliable blood biomarkers that facilitate an appropriate screening of veterans for brain pathology need to be discovered. A liquid biopsy approach involving analysis of brain-derived extracellular vesicles in the blood appears efficient for discerning the extent of neuropathology both before and during clinical trials.

Brainstem atrophy in Gulf War Illness

BACKGROUND

Gulf War Illness (GWI) is a condition that affects about 30 % of veterans who served in the 1990-91 Persian Gulf War. Given its broad symptomatic manifestation, including chronic pain, fatigue, neurological, gastrointestinal, respiratory, and skin problems, it is of interest to examine whether GWI is associated with changes in the brain. Existing neuroimaging studies, however, have been limited by small sample sizes, inconsistent GWI diagnosis criteria, and potential comorbidity confounds.

OBJECTIVES

Using a large cohort of US veterans with GWI, we assessed regional brain volumes for their associations with GWI, and quantified the relationships between any regional volumetric changes and GWI symptoms.

METHODS

Structural magnetic resonance imaging (MRI) scans from 111 veterans with GWI (Age = 49 ± 6, 88 % Male) and 59 healthy controls (age = 51 ± 9, 78 % male) were collected at the California War Related Illness and Injury Study Center (WRIISC-CA) and from a multicenter study of the Parkinson's Progression Marker Initiative (PPMI), respectively. Individual MRI volumes were segmented and parcellated using FreeSurfer. Regional volumes of 19 subcortical, 68 cortical, and 3 brainstem structures were evaluated in the GWI cohort relative to healthy controls. The relationships between regional volumes and GWI symptoms were also assessed.

RESULTS

We found significant subcortical atrophy, but no cortical differences, in the GWI group relative to controls, with the largest effect detected in the brainstem, followed by the ventral diencephalon and the thalamus. In a subsample of 58 veterans with GWI who completed the Chronic Fatigue Scale (CFS) inventory of Centers for Disease Control and Prevention (CDC), smaller brainstem volumes were significantly correlated with increased severities of fatigue and depressive symptoms.

CONCLUSION

The findings suggest that brainstem volume may be selectively affected by GWI, and that the resulting atrophy could in turn mediate or moderate GWI-related symptoms such as fatigue and depression. Consequently, the brain stem should be carefully considered in future research focusing on GWI pathology.

Neuroinflammation in Gulf War Illness is linked with HMGB1 and complement activation, which can be discerned from brain-derived extracellular vesicles in the blood

Cognitive dysfunction and neuroinflammation are conspicuously observed in Gulf War Illness (GWI). We investigated whether brain inflammation in GWI is associated with activation of high mobility group box-1 (HMGB1) and complement-related proteins in neurons and astrocytes, and brain inflammation can be tracked through neuron-derived extracellular vesicles (NDEVs) and astrocyte-derived EVs (ADEVs) found in the circulating blood. We exposed animals to GWI-related chemicals pyridostigmine bromide, DEET and permethrin, and moderate stress for 28 days. We performed behavioral tests 10 months post-exposure and quantified activated microglia and reactive astrocytes in the cerebral cortex. Then, we measured the concentration of HMGB1, proinflammatory cytokines, and complement activation-related proteins in the cerebral cortex, and NDEVs and ADEVs in the circulating blood. Cognitive impairments persisted in GWI rats at 10 months post-exposure, which were associated with increased density of activated microglia and reactive astrocytes in the cerebral cortex. Moreover, the level of HMGB1 was elevated in the cerebral cortex with altered expression in the cytoplasm of neuronal soma and dendrites as well as the extracellular space. Also, higher levels of proinflammatory cytokines (TNFa, IL-1b, and IL-6), and complement activation-related proteins (C3 and TccC5b-9) were seen in the cerebral cortex. Remarkably, increased levels of HMGB1 and proinflammatory cytokines observed in the cerebral cortex of GWI rats could also be found in NDEVs isolated from the blood. Similarly, elevated levels of complement proteins seen in the cerebral cortex could be found in ADEVs. The results provide new evidence that persistent cognitive dysfunction and chronic neuroinflammation in a model of GWI are linked with elevated HMGB1 concentration and complement activation. Furthermore, the results demonstrated that multiple biomarkers of neuroinflammation could be tracked reliably via analyses of NDEVs and ADEVs in the circulating blood. Execution of such a liquid biopsy approach is especially useful in clinical trials for monitoring the remission, persistence or progression of brain inflammation in GWI patients with drug treatment.

Gulf War illness associated with abnormal auditory P1 event-related potential: Evidence of impaired cholinergic processing replicated in a national sample

Our team previously reported event-related potential (ERP) and hyperarousal patterns from a study of one construction battalion of the U.S. Naval Reserve who served during the 1991 Persian Gulf War. We sought to replicate these findings in a sample that was more representative of the entire Gulf War-era veteran population, including male and female participants from four branches of the military. We collected ERP data from 40 veterans meeting Haley criteria for Gulf War syndromes 1-3 and from 22 matched Gulf War veteran controls while they performed an auditory oddball task. Reports of hyperarousal from the ill veterans were significantly greater than those from the control veterans, and P1 amplitudes in Syndromes 2 and 3 were significantly higher than P1 amplitudes in Syndrome 1, replicating our previous findings. Many of the contributors to the generation of the P1 potential are also involved in the regulation of arousal and are modulated by cholinergic and dopaminergic systems-two systems whose dysfunction has been implicated in Gulf War illness. These differences among the three syndrome groups where their means were on either side of controls is a replication of our previous ERP study and is consistent with previous imaging studies of this population.

Activity of Paraoxonase/Arylesterase and Butyrylcholinesterase in Peripheral Blood of Gulf War Era Veterans With Neurologic Symptom Complexes or Post-Traumatic Stress Disorder

OBJECTIVE

Two groups of Gulf War era veterans, one exhibiting blurred vision, balance problems/dizziness, tremors/shaking, and speech difficulty and a second group with post-traumatic stress disorder (PTSD), but not the neurologic syndrome, were assessed for organophosphate-detoxifying enzyme paraoxonase/arylesterase (PON1) and its Q/R isoforms, butyrylcholinesterase (BuChE) and its U/A isoforms and cytokines.

METHODS

Defibrinated peripheral blood was evaluated for enzymes and cytokines.

RESULTS

Trends toward elevation of Th2 cytokines interleukin-4 (IL-4) and IL-13 were observed in subjects with neurologic syndrome. Neither the activities nor isoforms of the enzyme, the neurologic symptoms, nor PTSD had any relationship to wartime deployment to the theater of combat.

CONCLUSION

The negative outcomes described above suggest that exposure to organophosphates or other agents normally detoxified by PON1 and BuChE may not have contributed significantly to neurologic components of Gulf War Illness.

Parvalbumin and neuropeptide Y expressing hippocampal GABA-ergic inhibitory interneuron numbers decline in a model of Gulf War illness

Cognitive dysfunction is amongst the most conspicuous symptoms in Gulf War illness (GWI). Combined exposure to the nerve gas antidote pyridostigmine bromide (PB), pesticides and stress during the Persian Gulf War-1 (PGW-1) are presumed to be among the major causes of GWI. Indeed, our recent studies in rat models have shown that exposure to GWI-related (GWIR) chemicals and mild stress for 4 weeks engenders cognitive impairments accompanied with several detrimental changes in the hippocampus. In this study, we tested whether reduced numbers of hippocampal gamma-amino butyric acid (GABA)-ergic interneurons are among the pathological changes induced by GWIR-chemicals and stress. Animals were exposed to low doses of GWIR-chemicals and mild stress for 4 weeks. Three months after this exposure, subpopulations of GABA-ergic interneurons expressing the calcium binding protein parvalbumin (PV), the neuropeptide Y (NPY) and somatostatin (SS) in the hippocampus were stereologically quantified. Animals exposed to GWIR-chemicals and stress for 4 weeks displayed reduced numbers of PV-expressing GABA-ergic interneurons in the dentate gyrus and NPY-expressing interneurons in the CA1 and CA3 subfields. However, no changes in SS+ interneuron population were observed in the hippocampus. Furthermore, GABA-ergic interneuron deficiency in these animals was associated with greatly diminished hippocampus neurogenesis. Because PV+ and NPY+ interneurons play roles in maintaining normal cognitive function and neurogenesis, and controlling the activity of excitatory neurons in the hippocampus, reduced numbers of these interneurons may be one of the major causes of cognitive dysfunction and reduced neurogenesis observed in GWI. Hence, strategies that improve inhibitory neurotransmission in the hippocampus may prove beneficial for reversing cognitive dysfunction in GWI.

Multiple sclerosis in gulf war era veterans. 2. Military deployment and risk of multiple sclerosis in the first gulf war

BACKGROUND

Concern has been raised that US veterans of the 1990-1991 Gulf War (GW1) may be at increased risk to develop neurologic disease.

METHODS

An incident cohort of multiple sclerosis (MS) and other demyelinating disease (ODD) was assembled from the US military comprising the Gulf War era (1990-2007). Cases of MS and ODD meeting standard diagnostic criteria were matched to a database of all active duty personnel from the Department of Defense. Relative risk (RR) estimates for MS and all demyelinating disease based on onset, deployment status, and exposures were calculated.

RESULTS

For GW1, a total of 1,841 incident cases of definite MS and ODD were identified, with 387 among 696,118 deployed and 1,454 among 1,786,215 nondeployed personnel. The RR for MS alone among those deployed compared to those nondeployed was 0.69 (confidence interval, CI: 0.61-0.78), with 0.72 (CI: 0.62-0.83) in men and 0.96 (CI: 0.75-1.22) in women. Deployment was also nonsignificant or protective as an MS risk factor across racial groups, all age groups, and each military service. RRs for MS by service were: Air Force 0.71 (CI: 0.53-0.96), Army 0.80 (CI: 0.67-0.96), Marines 0.96 (CI: 0.63-1.47), and Navy 0.56 (CI: 0.43-0.74).

CONCLUSION

Military deployment to GW1 was not a risk factor for developing MS.

Object location and object recognition memory impairments, motivation deficits and depression in a model of Gulf War illness

Memory and mood deficits are the enduring brain-related symptoms in Gulf War illness (GWI). Both animal model and epidemiological investigations have indicated that these impairments in a majority of GW veterans are linked to exposures to chemicals such as pyridostigmine bromide (PB, an antinerve gas drug), permethrin (PM, an insecticide) and DEET (a mosquito repellant) encountered during the Persian Gulf War-1. Our previous study in a rat model has shown that combined exposures to low doses of GWI-related (GWIR) chemicals PB, PM, and DEET with or without 5-min of restraint stress (a mild stress paradigm) causes hippocampus-dependent spatial memory dysfunction in a water maze test (WMT) and increased depressive-like behavior in a forced swim test (FST). In this study, using a larger cohort of rats exposed to GWIR-chemicals and stress, we investigated whether the memory deficiency identified earlier in a WMT is reproducible with an alternative and stress free hippocampus-dependent memory test such as the object location test (OLT). We also ascertained the possible co-existence of hippocampus-independent memory dysfunction using a novel object recognition test (NORT), and alterations in mood function with additional tests for motivation and depression. Our results provide new evidence that exposure to low doses of GWIR-chemicals and mild stress for 4 weeks causes deficits in hippocampus-dependent object location memory and perirhinal cortex-dependent novel object recognition memory. An open field test performed prior to other behavioral analyses revealed that memory impairments were not associated with increased anxiety or deficits in general motor ability. However, behavioral tests for mood function such as a voluntary physical exercise paradigm and a novelty suppressed feeding test (NSFT) demonstrated decreased motivation levels and depression. Thus, exposure to GWIR-chemicals and stress causes both hippocampus-dependent and hippocampus-independent memory impairments as well as mood dysfunction in a rat model.

Mood and memory deficits in a model of Gulf War illness are linked with reduced neurogenesis, partial neuron loss, and mild inflammation in the hippocampus

Impairments in mood and cognitive function are the key brain abnormalities observed in Gulf war illness (GWI), a chronic multisymptom health problem afflicting ∼25% of veterans who served in the Persian Gulf War-1. Although the precise cause of GWI is still unknown, combined exposure to a nerve gas prophylaxis drug pyridostigmine bromide (PB) and pesticides DEET and permethrin during the war has been proposed as one of the foremost causes of GWI. We investigated the effect of 4 weeks of exposure to Gulf war illness-related (GWIR) chemicals in the absence or presence of mild stress on mood and cognitive function, dentate gyrus neurogenesis, and neurons, microglia, and astrocytes in the hippocampus. Combined exposure to low doses of GWIR chemicals PB, DEET, and permethrin induced depressive- and anxiety-like behavior and spatial learning and memory dysfunction. Application of mild stress in the period of exposure to chemicals exacerbated the extent of mood and cognitive dysfunction. Furthermore, these behavioral impairments were associated with reduced hippocampal volume and multiple cellular alterations such as chronic reductions in neural stem cell activity and neurogenesis, partial loss of principal neurons, and mild inflammation comprising sporadic occurrence of activated microglia and significant hypertrophy of astrocytes. The results show the first evidence of an association between mood and cognitive dysfunction and hippocampal pathology epitomized by decreased neurogenesis, partial loss of principal neurons, and mild inflammation in a model of GWI. Hence, treatment strategies that are efficacious for enhancing neurogenesis and suppressing inflammation may be helpful for alleviation of mood and cognitive dysfunction observed in GWI.

Memory impairment exhibited by veterans with Gulf War Illness

Roughly 26-32% of US veterans, who served in the first Gulf War, report suffering from chronic health problems ( Golomb, 2008 , Proceedings of the National Academies of Science, 105, 4295). The present study investigated the memory deficits reported by these ill Gulf War veterans (GWV) using a face-name associative memory paradigm administered during functional magnetic resonance imaging (fMRI). The fMRI data confirmed memory performance on the memory task to be related to the amount of activation in the left hippocampus observed during the study. In addition, ill-GWV demonstrated decreased memory performance relative to unaffected GWV on this memory test, providing evidence of memory deficits using an objective measure of memory.

Visual event-related potentials as markers of hyperarousal in Gulf War illness: evidence against a stress-related etiology

An exaggerated response to emotional stimuli is among the many symptoms widely reported by veterans of the 1991 Persian Gulf War. These symptomologies have been attributed to damage and dysfunction associated with deployment-related exposures. We collected event-related potential data from 22 veterans meeting Haley criteria for Gulf War (GW) Syndromes 1-3 and from 8 matched GW veteran controls, who were deployed but not symptomatic, while they performed a visual three-condition oddball task where images authenticated to be associated with the 1991 Persian Gulf War were the distractor stimuli. Hyperarousal reported by ill veterans was significantly greater than that by control veterans, but this was not paralleled by higher amplitude P3a in their ERP responses to GW-related distractor stimuli. Whereas previous studies of PTSD patients have shown higher amplitude P3b responses to target stimuli that are placed amid trauma-related nontarget stimuli, ill veterans in this study showed P3b amplitudes to target stimuli - placed amid GW-related nontarget stimuli - that were significantly lower than those of the control group. Hyperarousal scores reliably predicted P3b, but not P3a, amplitudes. Although many factors may contribute to P3b amplitude differences - most notably depression and poor sleep quality, symptoms that are prevalent in the GW syndrome groups - our findings in context of previous studies on this population are consistent with the contention that dysfunction in cholinergic and dopaminergic neurotransmitter systems, and in white matter and basal ganglia may be contributing to impairments in GW veterans.

Event-related potential patterns associated with hyperarousal in Gulf War illness syndrome groups

An exaggerated response to emotional stimuli is one of the several symptoms widely reported by veterans of the 1991 Persian Gulf War. Many have attributed these symptoms to post-war stress; others have attributed the symptoms to deployment-related exposures and associated damage to cholinergic, dopaminergic, and white matter systems. We collected event-related potential (ERP) data from 20 veterans meeting Haley criteria for Gulf War Syndromes 1-3 and from 8 matched Gulf War veteran controls, who were deployed but not symptomatic, while they performed an auditory three-condition oddball task with gunshot and lion roar sounds as the distractor stimuli. Reports of hyperarousal from the ill veterans were significantly greater than those from the control veterans; different ERP profiles emerged to account for their hyperarousability. Syndromes 2 and 3, who have previously shown brainstem abnormalities, show significantly stronger auditory P1 amplitudes, purported to indicate compromised cholinergic inhibitory gating in the reticular activating system. Syndromes 1 and 2, who have previously shown basal ganglia dysfunction, show significantly weaker P3a response to distractor stimuli, purported to indicate dysfunction of the dopaminergic contribution to their ability to inhibit distraction by irrelevant stimuli. All three syndrome groups showed an attenuated P3b to target stimuli, which could be secondary to both cholinergic and dopaminergic contributions or disruption of white matter integrity.

FMRI reveals abnormal central processing of sensory and pain stimuli in ill Gulf War veterans

Many veterans chronically ill from the 1991 Gulf War exhibit symptoms of altered sensation, including chronic pain. In this study of 55 veterans of a Construction Battalion previously examined in 1995-1996 and 1997-1998, brain activation to innocuous and noxious heat stimuli was assessed in 2008-2009 with a quantitative sensory testing fMRI protocol in control veterans and groups representing three syndrome variants. Testing outside the scanner revealed no significant differences in warm detection or heat pain threshold among the four groups. In the fMRI study, Syndrome 1 and Syndrome 2, but not Syndrome 3, exhibited hypo-activation to innocuous heat and hyper-activation to noxious heat stimuli compared to controls. The results indicate abnormal central processing of sensory and painful stimuli in 2 of 3 variants of Gulf War illness and call for a more comprehensive study with a larger, representative sample of veterans.

Organophosphates dysregulate dopamine signaling, glutamatergic neurotransmission, and induce neuronal injury markers in striatum

The neurological effects of organophosphate (OP) pesticides, commonly used on foods and in households, are an important public health concern. Furthermore, subclinical exposure to combinations of organophosphates is implicated in Gulf War illness. Here, we characterized the effects of the broadly used insecticide chlorpyrifos (CPF) on dopamine and glutamatergic neurotransmission effectors in corticostriatal motor/reward circuitry. CPF potentiated protein kinase A (PKA)-dependent phosphorylation of the striatal protein dopamine- and cAMP-regulated phosphoprotein of M(r) 32 kDa (DARPP-32) and the glutamate receptor 1 (GluR1) subunit of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors in mouse brain slices. It also increased GluR1 phosphorylation by PKA when administered systemically. This correlated with enhanced glutamate release from cortical projections in rat striatum. Similar effects were induced by the sarin congener, diisopropyl fluorophosphate, alone or in combination with the putative neuroprotectant, pyridostigmine bromide and the pesticide N,N-diethyl-meta-toluamide (DEET). This combination, meant to mimic the neurotoxicant exposure encountered by veterans of the 1991 Persian Gulf War, also induced hyperphosphorylation of the neurofibrillary tangle-associated protein tau. Diisopropyl fluorophosphate and pyrodostigmine bromide, alone or in combination, also increased the aberrant activity of the protein kinase, Cdk5, as indicated by conversion of its activating cofactor p35 to p25. Thus, consistent with recent findings in humans and animals, organophosphate exposure causes dysregulation in the motor/reward circuitry and invokes mechanisms associated with neurological disorders and neurodegeneration.

Periodic limb movements in sleep exhibit a circadian rhythm that is maximal in the late evening/early night

OBJECTIVE

Periodic limb movements in sleep (PLMS) show a time-of-night pattern, with most movements at the beginning of the night. Our study aimed to determine whether this pattern is due to an endogenous circadian rhythm, like that in the related movement disorder Restless Legs Syndrome (RLS).

METHODS

Four healthy older adults with a screening PLMI>20 were studied in an inpatient forced desynchrony protocol with an imposed sleep-wake cycle of 20 h for 12 "nights," allowing separation of circadian and sleep homeostatic influences on leg movements. We recorded sleep polysomnographically throughout each scheduled episode, including left and right anterior tibialis EMG.

RESULTS

PLMS in Stage 2 showed both a significant time-within-sleep pattern and a significant circadian rhythm. The circadian rhythm in PLMS peaked at the circadian phases when usual sleep onset occurs, preceding the evening rise in melatonin secretion.

CONCLUSIONS

In our subjects, the circadian pattern of PLMs expression was very similar to that previously reported in patients with RLS. This evidence for a circadian rhythm in PLMS has implications for treatment and provides direction for future studies of the pathophysiology of this movement disorder.

Impaired response inhibition in ill Gulf War veterans

Poor performance on tasks requiring response inhibition has been observed among chronically ill veterans of the 1991 Persian Gulf War. Semantic difficulties have also been reported. We collected event-related potential (ERP) and behavioral data from 25 Gulf War veterans who complained of cognitive difficulties and from 23 matched controls, who were deployed but not symptomatic, while they performed a GO-NOGO task that required both a semantic decision and inhibitory processing. A significantly greater false-alarm rate among the ill veterans was accompanied in the ERP data by significantly reduced amplitude in the NOGO P3, consistent with previous ERP studies of other patient groups that have shown poor inhibitory response performance. This supports the contention that the ill veterans' deficit lies more in inhibiting than in detecting task-related differences in the stimuli.

[Retrospective study of ALS in French military personnel]

INTRODUCTION

An apparent increased risk for developing Amyotrophic Lateral Sclerosis (ALS), a multifactorial neurodegenerative disease, is considered to exist in the military population.

PATIENTS AND METHODS

ALS military and veteran patients were retrospectively recruited in April 2008 by searching medical data (Hippocrate) and repayment data (Erasme) of the French National Military Health Care Fund (Caisse nationale militaire de sécurité sociale, CNMSS) from de January 1991 to December 2007.

RESULTS

We report a series of 73 patients, 69 male and four female, average age of 52.5 years (range 27 to 72 years) with a peak of patients in the 50-59 year age class. The branch of military service was Army (n=26 patients), Air force (n=14), Navy (n=10) and State Police Force (n=22). The incidence among male active duty military personnel was stable from 2002 to 2007; it was less than the general population (1.7/100,000 per year in 2007), but higher in the 40-44 and 50-54 year age classes (1.90 and 5.07/100,000 per year in 2007 respectively). Duration of active duty was on average 31 years.

CONCLUSION

The retrospective nature of the data and the incomplete population with loss of retired military personnel without CNMSS affiliation are limitations of our study. Another means of collecting all cases of ALS among French military personnel and veterans would be to conduct a search in the 17 ALS centers in France with analysis by occupational activity for entire career.

Pituitary response to metyrapone in Gulf War veterans: relationship to deployment, PTSD and unexplained health symptoms

OBJECTIVE

Gulf War deployment has been associated with a distinct neuroendocrine profile characterized by low 24h basal ACTH levels and enhanced cortisol and ACTH suppression to low-dose dexamethasone. The metyrapone stimulation test was performed to further characterize hypothalamic-pituitary activity in Gulf War veterans (GWV) and its relationship to unexplained medical symptoms and post-traumatic stress disorder (PTSD).

METHOD

Eleven GWV without PTSD, 18 GWV with PTSD and 15 healthy subjects not exposed to the Gulf War theater (non-exposed) underwent the metyrapone stimulation test, which inhibits cortisol synthesis, impairs cortisol-mediated negative feedback inhibition and in turn increases levels of ACTH and 11-deoxycortisol, a cortisol precursor. These hormones were measured at baseline (7:00 a.m.) and at intervals (from 8:00 a.m. to 4:00 p.m.) following the administration of metyrapone 750mg orally at 7:05 a.m. and at 10:05 a.m.

RESULTS

There were group differences in the ACTH response despite similar cortisol and 11-deoxycortisol responses to metyrapone. GWV without PTSD had a significantly attenuated ACTH response compared to non-exposed subjects; GWV with PTSD had a significantly higher ACTH response than GWV without PTSD but did not differ from non-exposed subjects. Among GWV, unexplained medical health symptoms (e.g., neurological, musculoskeletal, cardiac, and pulmonary symptoms) and PTSD symptoms were significantly positively associated with the ACTH response to metyrapone.

CONCLUSION

Gulf War deployment is associated with a substantially lower ACTH response to metyrapone. In contrast, unexplained health symptoms and PTSD in Gulf War veterans are associated with relatively greater hypothalamic-pituitary activity which may reflect increased CRF activity and is evident only in consideration of deployment effects. This pattern of differences suggests either that Gulf War deployment and its associated exposures results in enduring changes in pituitary function or that reduced hypothalamic-pituitary activity protects against the development of PTSD and other deployment-related health problems.

Neurological mortality among U.S. veterans of the Persian Gulf War: 13-year follow-up

BACKGROUND

This study focuses on long-term mortality, specifically brain cancer, amyotrophic lateral sclerosis (ALS), Parkinson's disease, and multiple sclerosis (MS) of 621,902 veterans who served in the 1990-1991 Persian Gulf War (GW), and 746,248 non-GW veterans.

METHODS

Follow-up began with the date the veteran left the GW theater or May 1, 1991 and ended with the date of death or December 31, 2004. Cox proportional hazard models were used for analyses.

RESULTS

Adjusted mortality rate ratios (aRR) of GW veterans compared to non-GW veterans were not statistically significant for brain cancer (aRR = 0.90, 95% confidence interval (CI): 0.73, 1.11), MS (aRR = 0.61, 95% CI: 0.23, 1.63), Parkinson's disease (aRR = 0.71, 95% CI: 0.17, 2.99), or ALS (aRR = 0.96, 95% CI: 0.56, 1.62). GW veterans potentially exposed to nerve agents for 2 or more days and GW veterans exposed to oil well fire smoke were at increased risk for brain cancer mortality (aRR = 2.71, 95% CI: 1.25, 5.87; aRR = 1.81, 95% CI: 1.00, 3.27; respectively).

CONCLUSIONS

The risk of death due to ALS, MS, Parkinson's disease, and brain cancer was not associated with 1991 GW service in general. However, GW veterans potentially exposed to nerve agents at Khamisiyah, Iraq, and to oil well fire smoke had an increased risk of mortality due to brain cancer.

Abnormal brain response to cholinergic challenge in chronic encephalopathy from the 1991 Gulf War

Several case definitions of chronic illness in veterans of the 1991 Persian Gulf War have been linked epidemiologically with environmental exposure to cholinesterase-inhibiting chemicals, which cause chronic changes in cholinergic receptors in animal models. Twenty-one chronically ill Gulf War veterans (5 with symptom complex 1, 11 with complex 2, and 5 with complex 3) and 17 age-, sex- and education-matched controls, underwent an 99mTc-HMPAO-SPECT brain scan following infusion of saline and >48 h later a second scan following infusion of physostigmine in saline. From each SPECT image mean normalized regional cerebral blood flow (nrCBF) from 39 small blocks of correlated voxels were extracted with geostatistical spatial modeling from eight deep gray matter structures in each hemisphere. Baseline nrCBF in symptom complex 2 was lower than controls throughout deep structures. The change in nrCBF after physostigmine (challenge minus baseline) was negative in complexes 1 and 3 and controls but positive in complex 2 in some structures. Since effects were opposite in different groups, no finding typified the entire patient sample. A hold-out discriminant model of nrCBF from 17 deep brain blocks predicted membership in the clinical groups with sensitivity of 0.95 and specificity of 0.82. Gulf War-associated chronic encephalopathy in a subset of veterans may be due to neuronal dysfunction, including abnormal cholinergic response, in deep brain structures.

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.

Multiple vaccine and pyridostigmine interactions: Effects on cognition, muscle function and health outcomes in marmosets

Following active service during the 1990/1991 Gulf Conflict, a number of UK and US veterans presented with a diverse range of symptoms, collectively known as Gulf Veterans Illnesses (GVI). The administration of vaccines and/or the pretreatment against possible nerve agent poisoning, pyridostigmine bromide (PB), given to armed forces personnel during the Gulf Conflict has been implicated as a possible factor in the aetiology of these illnesses. The possibility that long-term health effects may result from the administration of these vaccines (anthrax, pertussis, plague, yellow fever, polio, typhoid, tetanus, hepatitis B, meningococcal meningitis and cholera) and/or PB, have been investigated using a non-human primate model, the common marmoset. This paper reports the results from three aspects of the study, cognitive behaviour (performance of a touchscreen mediated discrimination task), muscle function (performance of a simple strength test) and general health. There were no marked long-term changes in cognition, muscle function or health that could be attributed to vaccines and/or PB administration. Statistical differences related to treatments were only observed in two aspects of cognition and one of clinical chemistry. These changes were transient in nature and their magnitude were minor and, in consequence, was not regarded as having long-term biological significance.

Using a white matter reference to remove the dependency of global signal on experimental conditions in SPECT analyses

Proportional scaling models are often used in functional imaging studies to remove confounding of local signals by global effects. It is generally assumed that global effects are uncorrelated with experimental conditions. However, when the global effect is estimated by the global signal, defined as the intracerebral average, incorrect inference may result from the dependency of the global signal on preexisting conditions or experimental manipulations. In this paper, we propose a simple alternative method of estimating the global effect to be used in a proportional scaling model. Specifically, by defining the global signal with reference strictly to a white matter region within the centrum semiovale, the dependency is removed in experiments where white matter is unaffected by the disease effect or experimental treatments. The increase in the ability to detect changes in regional blood flow is demonstrated in a SPECT study of healthy and ill Gulf War veterans in whom it is suspected that brain abnormalities influence the traditional calculation of the global signal. Controlling for the global effect, ill veterans have significantly lower intracerebral averages than healthy controls (P = 0.0038), evidence that choice of global signal has an impact on inference. Scaling by the modified global signal proposed here results in an increase in sensitivity leading to the identification of several regions in the insula and frontal cortex where ill veterans have significantly lower SPECT emissions. Scaling by the traditional global signal results in the loss of sensitivity to detect these regional differences. Advantages of this alternative method are its computational simplicity and its ability to be easily integrated into existing analysis frameworks such as SPM.

The impact of the 1991 Gulf War on the mind and brain: findings from neuropsychological and neuroimaging research

Many veterans of the 1991 Gulf War (GW) have complained of somatic and cognitive symptoms that may be neurological in nature. However, whether or not changes in brain function are associated with GW service continues to be debated. Studies of GW veterans using objective, performance-based neuropsychological measures have yielded inconsistent findings, with those indicating deficits among GW veterans typically revealing only relatively mild levels of neuropsychological impairment. Further, performances on objective neuropsychological tasks show little correspondence to subjective perceptions of cognitive functioning. Although preliminary magnetic resonance spectroscopy (MRS) studies demonstrate reduced N-acetylaspartate-to-creatine (NAA/Cr) ratio in select brain regions among GW veterans who report health concerns, this work requires further replication with larger, more representative samples. There is no evidence from neuroimaging studies of a non-specific effect of GW service or of changes in brain structure or function related to health status when conventional radiological methods are used. Owing to the paucity of objective exposure, baseline health data, and the now significant time elapsed since the GW, aetiological issues may never be fully resolved. Therefore, research addressing clinical management of GW veterans with neuropsychological dysfunction and neuroimaging abnormalities may prove more fruitful than exclusive focus on aetiology.

Neurological status of Australian veterans of the 1991 Gulf War and the effect of medical and chemical exposures

BACKGROUND

Since the 1991 Gulf War, concerns have been voiced about the effects on the health of veterans of Gulf War related medical and chemical exposures.

METHODS

Our cross-sectional study compared 1424 male Australian Gulf War veterans and a randomly sampled military comparison group (n = 1548). A postal questionnaire asked about the presence of current neurological type symptoms, medically diagnosed neurological conditions, and medical and chemical exposures. A neurological examination was performed as part of a physical assessment.

RESULTS

Veterans have a higher prevalence of neurological type symptoms (ratio of means 1.4, 95% confidence interval (CI) 1.2-1.5). Although the odds ratio (OR) of lower limb neurological type symptoms and signs in veterans compared with the comparison group was increased (OR = 1.6, 95% CI 1.0-2.7), it was of borderline significance, and there was no difference between groups according to a Neuropathy Score based on neurological signs alone (ratio of means 1.1, 95% CI 0.9-1.3). The increased OR of neurological type symptoms and signs suggestive of a central nervous system disorder (OR = 1.8, 95% CI 1.0-3.1) was also of borderline significance. Veterans were not more likely to have self-reported medically diagnosed neurological conditions, or to have neurological type symptoms and signs suggestive of an anterior horn cell disorder (OR = 0.9, 95% CI 0.5-1.6). The total number of neurological type symptoms reported by veterans, but not the Neuropathy Score, was associated with Gulf War related exposures including immunizations and pyridostigmine bromide in dose-response relationships, anti-biological warfare tablets, solvents, pesticides, and insect repellents.

CONCLUSIONS

This study shows increased reporting of neurological type symptoms in Gulf War veterans, but no evidence for increased neurological effects based on objective physical signs. There may be a number of factors, including information bias, relating to increased neurological type symptom reporting in veterans.

Acute effects of pulsed microwaves and 3-nitropropionic acid on neuronal ultrastructure in the rat caudate-putamen

Ultrastructure of the medium sized "spiny" neuron in rat dorsal-lateral caudate-putamen was assessed after administration of 3-nitropropionic acid (3-NP) and exposure to pulsed microwaves. Sprague-Dawley male rats were given two daily intraperitoneal doses of 0 or 10 mg/kg 3-NP and 1.5 h after each dose were exposed to microwave radiation at a whole body averaged specific absorption rate (SAR) of 0 (sham exposure), 0.6, or 6 W/kg for 30 min. Microwave exposure consisted of 1.25 GHz radiation delivered as 5.9 micros pulses with repetition frequency 10 Hz. Tissue samples taken 2-3 h after the second sham or microwave exposure showed no injury with light microscope methods. Blinded qualitative assessment of ultrastructure of randomly selected neurons from the same samples did reveal differences. Subsequent detailed, quantitative measurements showed that, when followed by sham exposure, administration of 3-NP significantly increased endoplasmic reticulum (ER) intracisternal width, ER area density, and nuclear envelope thickness. Microwave exposure at 6 W/kg alone also significantly increased these measures. Exposure of 3-NP treated animals at 6 W/kg significantly increased effects of 3-NP on ultrastructure. Although exposure at 0.6 W/kg alone did not affect ultrastructure measures, exposure of 3-NP treated animals at 0.6 W/kg reduced the effects of 3-NP. We concluded that 3-NP changed neuronal ultrastructure and that the microwave exposures used here changed neuronal ultrastructure in ways that depended on microwave SAR and neuron metabolic status. The apparent cancellation of 3-NP induced changes by exposure to pulsed microwaves at 0.6 W/kg indicated the possibility that such exposure can protect against the effects of mitochondrial toxins on the nervous system.

Resolving Disputes About Toxicological Risks During Military Conflict

In the last 15 years, the US and UK have fought two major wars in the Persian Gulf region. Controversy has arisen over the nature and causes of health problems among military veterans of these two wars. Toxic exposures have been hypothesised to cause the majority of the long-term health problems experienced by veterans of the 1991 Gulf War. The assessment of these toxic exposures and the resolution of controversy about their health effects provide a unique case study for understanding how toxicological disputes are settled in the US. Neither clinical examination of ill war veterans nor scientific research studies have been sufficient to answer contentious questions about toxic exposures. Numerous expert review panels have also been unable to resolve these controversies except for the US National Academy of Sciences Institute of Medicine (IOM). The IOM has conducted exhaustive and independent investigations based on peer-reviewed scientific literature related to potential health risks during the two Gulf Wars. In four recent studies, IOM committees identified a wide range of previously documented illnesses associated with common occupational and environmental exposures after considering thousands of relevant publications; however, they did not identify a new medical syndrome or a specific toxic exposure that caused widespread health problems among Gulf War veterans. These IOM studies have, therefore, added little to our basic knowledge of environmental hazards because most of the health effects were well known. Nevertheless, this expert review process, which is on-going, has been generally acceptable to a wide range of competing interests because the findings of the IOM have been perceived as scientifically credible and independent, and because none of the postulated toxicological risks have been completely ruled-out as possible causes of ill health among veterans.

Blunted circadian variation in autonomic regulation of sinus node function in veterans with Gulf War syndrome

PURPOSE

To test the hypothesis that subtle abnormalities of the autonomic nervous system underlie the chronic symptoms reported by many Gulf War veterans, such as chronic diarrhea, dizziness, fatigue, and sexual dysfunction.

METHODS

Twenty-two ill Gulf War veterans and 19 age-, sex-, and education-matched control veterans underwent measurement of circadian rhythm of heart rate variability by 24-hour electrocardiography, ambulatory blood pressure recording, Valsalva ratio testing, sympathetic skin response evaluation, sweat imprint testing, and polysomnography. Investigators were blinded to case- or control-group status.

RESULTS

High-frequency spectral power of heart rate variability increased normally 2.2-fold during sleep in controls but only 1.2-fold in ill veterans (P <0.0001). In ill veterans as compared with controls, it was lower at night (P = 0.0006), higher during the morning (P = 0.007), but no different during the rest of the day (P = 0.8). The mean heart rate of ill veterans also declined less at night (P = 0.0002), and their corrected QT intervals tended to be longer over the full 24 hours (P = 0.07), particularly at night (P = 0.03). Blunting of the nocturnal heart rate dip in ill veterans was confirmed by 24-hour automatic ambulatory blood pressure monitoring (P = 0.05) and polysomnography (P = 0.03). These differences remained significant after adjusting for potential confounders. Cases and controls were similar on measures of sympathetic adrenergic and sudomotor function, sleep architecture, respiratory function, and circadian variation in blood pressure and body temperature.

CONCLUSION

Some symptoms of Gulf War syndrome may be due to subtle autonomic nervous system dysfunction.

After more than 10 years of Gulf War veteran medical evaluations, what have we learned?

Since the 1991 Gulf War, more than 10 years and 1 billion dollars of health evaluations and research have been invested in understanding illnesses among Gulf War veterans. We examined the extensive published healthcare utilization data in an effort to summarize what has been learned. Using multiple search techniques, data as of June 2003 from four different national Gulf War health registries and numerous hospitalization and ambulatory care reports were reviewed. Thus far, published reports have not revealed a unique Gulf War syndrome nor identified specific exposures that might explain postwar morbidity. Instead, they have demonstrated that Gulf War veterans have had an increase in multi-symptom condition, injury, and mental health diagnoses. While these diagnoses are similar to those experienced by other comparable military populations, their explanation is not fully understood. New strategies to identify risk factors for, and to reduce, such postdeployment conditions are summarized.

Is osteoporosis linked to vaccinations and Gulf War Syndrome?

Gulf War Syndrome (GWS) remains a contentious diagnosis with conflicting laboratory investigations and lack of a biologically plausible aetiology. Assertions have been made that GWS may be the result of vaccinations given to serving military personnel in the Persian Gulf and may be associated with osteoporosis. Calcitonin gene related protein (CGRP) is a vasoactive neuropeptide that is synthesised in conjunction with calcitonin gene expression. Vasoactive neuropeptides act as hormones, neurotransmitters, immune modulators and neurotrophes. They are readily catalysed to small peptide fragments. They and their binding sites are immunogenic and are known to be associated with a range of autoimmune conditions. This paper describes a biologically plausible mechanism for the development of osteoporosis in the context of GWS based on loss of immunological tolerance to the vasoactive neuropeptide CGRP or its receptors following a variety of antigenic events.

Is gulf war syndrome an autoimmune disorder of endogenous neuropeptides, exogenous sandfly maxadilan and molecular mimicry?

Gulf War Syndrome (GWS) remains a contentious diagnosis with conflicting laboratory investigation and lack of a biologically plausible aetiology. This paper discusses the potential role of maxadilan, a potent sandfly vasoactive peptide, in causing autoimmune responses in susceptible individuals through possible molecular mimicry with pituitary adenylate cyclase activating polypeptide (PACAP) and the PAC1R receptor. Gulf War Syndrome may share some causative pathology with Chronic Fatigue Syndrome (CFS), a disorder characterised by prolonged fatigue and debility mostly associated with post-infection sequelae although ongoing infection is unproven. Immunological aberration associated with an expanding group of vasoactive neuropeptides in the context of molecular mimicry and inappropriate immunological memory has been recently raised as possible cause of CFS. Vasoactive neuropeptides act as hormones, neurotransmitters, immune modulators and neurotrophes. They are readily catalysed to small peptide fragments. They and their binding sites are immunogenic and are known to be associated with a range of autoimmune conditions. Maxadilan, while not sharing substantial sequence homology with PACAP is a known agonist of the PACAP specific receptor (PAC1R) and therefore emulates these functions. Moreover a specific amino acid sequence peptide deletion within maxadilan converts it to a PACAP receptor antagonist raising the possibility of this substance provoking a CFS like response in humans exposed to it. This paper describes a biologically plausible mechanism for the development of a GWS-like chronic fatigue state based on loss of immunological tolerance to the vasoactive neuropeptide PACAP or its receptor following bites of the sandfly Phlebotomus papatasi and injection of the vasodilator peptide maxadilan. Exacerbation of this autoimmune response as a consequence of recent or simultaneous multiple vaccination exposures deserves further investigation. While the possible association between the relatively recently discovered vasoactive neuropeptides and chronic fatigue conditions has only recently been reported in the literature, this paper explores links for further research into GWS and CFS.

Disruption of the Blood–Brain Barrier and Neuronal Cell Death in Cingulate Cortex, Dentate Gyrus, Thalamus, and Hypothalamus in a Rat Model of Gulf-War Syndrome

We investigated the effects of a combined exposure to restraint stress and low doses of chemicals pyridostigmine bromide (PB), N, N-diethyl-m-toluamide (DEET), and permethrin in adult male rats, a model of Gulf-War syndrome. Animals were exposed daily to one of the following for 28 days: (i) a combination of stress and chemicals (PB, 1.3 mg/kg/day; DEET, 40 mg/kg/day; and permethrin, 0.13 mg/kg/day); (ii) stress and vehicle; (iii) chemicals alone; and (iv) vehicle alone. All animals were evaluated for: (i) the disruption of the blood-brain barrier (BBB) using intravenous horseradish peroxidase (HRP) injections and endothelial barrier antigen (EBA) immunostaining; (ii) neuronal cell death using H&E staining, silver staining, and glial fibrillary acidic protein (GFAP) immunostaining; and (iii) acetylcholinesterase (AChE) activity and m2-muscarinic acetylcholine receptors (m2-AChR). Animals subjected to stress and chemicals exhibited both disruption of the BBB and neuronal cell death in the cingulate cortex, the dentate gyrus, the thalamus, and the hypothalamus. Other regions of the brain, although they demonstrated some neuronal cell death, did not exhibit disruption of the BBB. The neuropathological changes in the above four brain regions were highly conspicuous and revealed by a large number of HRP-positive neurons (21-40% of total neurons), a decreased EBA immunostaining (42-51% reduction), a decreased number of surviving neurons (27-40% reduction), the presence of dying neurons (4-10% of total neurons), and an increased GFAP immunostaining (45-51% increase). These changes were also associated with decreased forebrain AChE activity and m2-AchR (19-25% reduction). In contrast, in animals exposed to stress and vehicle or chemicals alone, the above indices were mostly comparable to that of animals exposed to vehicle alone. Thus, a combined exposure to stress and low doses of PB, DEET, and permethrin leads to significant brain injury. The various neurological symptoms reported by Gulf-War veterans could be linked to this kind of brain injury incurred during the war.

Gulf war syndrome: could it be triggered by biological warfare-vaccines using pertussis as an adjuvant?

Several recent epidemiological studies have shown that vaccinations against biological warfare using pertussis as an adjuvant were associated with the Gulf war syndrome. If such epidemiological findings are confirmed, we propose that the use of pertussis as an adjuvant could trigger neurodegeneration through induction of interleukin-1beta secretion in the brain. In turn, neuronal lesions may be sustained by stress or neurotoxic chemical combinations. Particular susceptibility for IL-1beta secretion and potential distant neuronal damage could provide an explanation for the diversity of the symptoms observed on veterans.

Concordance across species in the reproductive and developmental toxicity of tetrachloroethylene

Reproductive and developmental toxicities resulting from exposure to tetrachloroethylene include delayed or impaired conception, sperm quality, death during development, developmental neurotoxicity, and growth retardation. In most cases there was concordance between rodents and humans. The risk assessments indicated that neurotoxicity was the most sensitive endpoint for inhalation, whereas growth retardation was the most sensitive endpoint when exposure was by the oral route. The reference concentration (RfC) of 0.01 ppm was based on neurotoxicity among human subjects. The reference dose (RfD) of 0.0006 mg/kg per day was based on small for gestation age infants. In both cases, studies in rodents supported the credibility of these assessments. For the RfD, similar findings for other trihalomethanes have been reported. The latter part of pregnancy and early life may constitute a susceptible period for alterations leading to behavioral deficits. During this period, the capacity to metabolize tetrachloroethylene is reduced and may further contribute to the sensitivity during this phase of development. Studies suggest that an effect on dopamine metabolism is a plausible mode of action for some types of neurotoxicity. In addition, it has been suggested that this alteration may affect reproductive integrity by influencing prolactin levels.

Methylphenidate increases the motor effects of L-Dopa in Parkinson's disease: a pilot study

We determined whether methylphenidate, a dopamine transporter blocker, modifies motor, cognitive, or affective responses to L-Dopa in Parkinson's disease (PD). Five patients who reported benefit from L-Dopa/carbidopa and motor fluctuations were admitted and withdrawn from their usual antiparkinsonian medications. On 3 consecutive days in a randomized double-blinded fashion, they took 0.2 mg/kg oral methylphenidate or placebo followed 30 minutes later by a 1-hour intravenous L-Dopa (2 mg/kg per h) or placebo infusion. Vital signs, tapping, walking, dyskinesias, mood, anxiety, concentration, and arousal were monitored every 30 minutes. Cognitive testing was performed before and following the infusion. Methylphenidate combined with L-Dopa led to greater peak right-hand tapping speed than either alone. Dyskinesia severity increased most when methylphenidate and L-Dopa were co-administered. There were no differences between conditions on the Stroop test, digit ordering, simple reaction time, or covert orienting of attention validity effect. Methylphenidate alone led to improvement in choice reaction time. Change in self-assessed analogue ratings of mood, anxiety, arousal, or concentration did not differ between conditions. Methylphenidate increased the motor effects of L-Dopa with minimal effects on cognitive or affective functions, suggesting a physiologic role for the dopamine transporter in patients with PD with motor fluctuations.

Use of structural equation modeling to test the construct validity of a case definition of Gulf War syndrome: invariance over developmental and validation samples, service branches and publicity

To attempt to replicate the syndrome-like structure identified by exploratory factor analysis of symptom reports from 249 Gulf War veterans of a Naval reserve battalion (the developmental sample), we administered Haley's original symptom questionnaire to 335 Gulf War veterans who served primarily in active-duty US Army units living in North Texas (the validation sample). On the basis of recently validated goodness-of-fit criteria (SRMR<or=0.08, RMSEA<or=0.06, and CFI>or=0.95), a structural equation model (Model 1) with four symptom scales loading on each of three first-order latent syndrome factors fit both the developmental and validation samples well and was invariant across both samples. Additional models validated a higher-order latent factor (a single Gulf War syndrome) explaining the variances and covariances of the first-order factors, four additional symptom scales loading on the higher-order factor, and four possible secondary factor loadings that also fit the data well. All structural models were invariant across cohorts of the validation sample surveyed before and after intense publicity following publication of the case definition. These findings suggest that the apparent syndrome structure of a single Gulf War syndrome with three variants may be found widely and justify a confirmatory sample survey of Gulf War-era veterans.