Inspiratory airflow dynamics during sleep in veterans with Gulf War illness: a controlled study

Bioenergetic impairment in Gulf War illness assessed via 31P-MRS

Time for post-exercise phosphocreatine-recovery (PCr-R), deemed a robust index of mitochondrial function in vivo, was previously reported to be elevated (signifying impaired ATP production) in veterans with Gulf War illness (GWI). Here we sought to replicate the finding and assess the impact of contravening previous eligibility requirements. The replication sample comprised white males. Cases reported ≥ moderate muscle-weakness to match the organ assessed to an organ affected; controls lacked recent headache or multiple symptoms. The expansion sample added cases without muscle-weakness, controls with recent headache, females, nonwhites. PCr-R, following pedal-depression-exercise, was compared in veterans with GWI versus controls (sample N = 38). In the replication sample, PCr-R results closely matched the prior report: PCr-R veterans with GWI mean(SD) = 47.7(16.5); control mean(SD) = 30.3(9.2), p = 0.017. (Prior-study PCr-R veterans with GWI mean(SD) = 46.1(17.9), control mean(SD) = 29.0(8.7), p = 0.023. Combined replication + prior samples: p = 0.001.) No case-control difference was observed in the expansion sample. In cases, PCr-R related to muscle-weakness: PCr-R = 29.9(7.1), 38.2(8.9), 47.8(15.2) for muscle-weakness rated none/low, intermediate, and high respectively (p for trend = 0.02), validating desirability of matching tissue assessed to tissue affected. In controls, headache/multiple symptoms, sex, and ethnicity each mattered (affecting PCr-R significantly). This study affirms mitochondrial/bioenergetic impairment in veterans with GWI. The importance of careful case/control selection is underscored.

Is exposure to chemical pollutants associated with sleep outcomes? A systematic review

Environmental exposures may influence sleep; however, the contributions of environmental chemical pollutants to sleep health have not been systematically investigated. We conducted a systematic review to identify, evaluate, summarize, and synthesize the existing evidence between chemical pollutants (air pollution, exposures related to the Gulf War and other conflicts, endocrine disruptors, metals, pesticides, solvents) and dimensions of sleep health (architecture, duration, quality, timing) and disorders (sleeping pill use, insomnia, sleep-disordered breathing)). Of the 204 included studies, results were mixed; however, the synthesized evidence suggested associations between particulate matter, exposures related to the Gulf War, dioxin and dioxin-like compounds, and pesticide exposure with worse sleep quality; exposures related to the Gulf War, aluminum, and mercury with insomnia and impaired sleep maintenance; and associations between tobacco smoke exposure with insomnia and sleep-disordered breathing, particularly in pediatric populations. Possible mechanisms relate to cholinergic signaling, neurotransmission, and inflammation. Chemical pollutants are likely key determinants of sleep health and disorders. Future studies should aim to evaluate environmental exposures on sleep across the lifespan, with a particular focus on developmental windows and biological mechanisms, as well as in historically marginalized or excluded populations.

Relationship between untreated obstructive sleep apnea and breath hydrogen and methane after glucose load

BACKGROUND

Patients with sleep disturbances have gastrointestinal symptoms. Breath hydrogen (H₂) and methane (CH₄) indicating small intestinal bacterial overgrowth (SIBO) might be related with these symptoms. The study was conducted to assess the link between breath profiles and untreated obstructive sleep apnea (OSA).

METHODS

: This prospective study enrolled consecutive patients with OSA using polysomnography. Heart rate variability (HRV) was used as a measurement for the balance of autonomic nervous system during polysomnography. Glucose breath test (GBT) to evaluate breath H₂ and CH₄ and bowel symptom questionnaire to investigate associated intestinal symptoms were performed.

RESULTS

Among 52 patients with OSA, 16 (30.8%) showed positivity to GBT. Although no significant difference was shown in GBT positivity between patients with healthy controls and patients with OSA (13.3% vs 30.8%, P = 0.109), breath H₂ and CH₄ levels in the OSA group were significantly higher than those in controls (P < 0.05). Flatulence was significantly common in OSA groups with GBT positivity than those without GBT positivity. Multivariate analysis demonstrated that waist-to-hip ratio (odds ratio = 12.889; 95% confidence interval (CI): 1.257-132.200; P = 0.031) and low-to-high-frequency ratio of HRV (odds ratio = 1.476; 95% CI: 1.013-2.151, P = 0.042) are independently related to GBT positivity in patients with OSA.

CONCLUSION

: Elevated breath H₂ or CH₄ after glucose load might not be an uncommon finding in patients with untreated OSA. Abdominal obesity and autonomic imbalance dysfunction are significantly associated with GBT positivity in OSA patients. SIBO could be considered as target for therapeutic management in OSA patients.

Gulf War veterans exhibit broadband sleep EEG power reductions in regions overlying the frontal lobe

AIMS

Nearly a third of U.S. veterans who deployed in support of the 1990-1991 Persian Gulf War are affected by Gulf War illness (GWI). Here we aimed to characterize whether subjective sleep complaints in GWI veterans are associated with objective sleep EEG disturbances relative to healthy veterans and controls; and whether Gulf War veterans show alterations in neural activity during sleep that differentiate them from healthy subjects.

MAIN METHODS

We used high-density EEG (HDEEG) to assess regional patterns of rapid eye movement (REM) sleep and non-REM (NREM) sleep between three groups: Gulf War male veterans with fatigue and GWI, Gulf War male veterans without fatigue or GWI, and control males. The groups were matched relative to age, sex and obstructive sleep apnea. Topographic comparisons of nocturnal NREM and REM sleep were made between groups for all frequency bands.

KEY FINDINGS

Topographic analysis revealed a broadband reduction in EEG power in a circumscribed region overlying the frontal lobe in both groups of Gulf War veterans, regardless of GWI and fatigue. This frontal reduction in neural activity was present, to some extent, across all frequency bands in NREM and REM sleep.

SIGNIFICANCE

Given that our findings were observed in all Gulf War veterans, it appears unlikely that frontal sleep HDEEG power reductions prove wholly responsible for fatigue symptoms. These results provide avenues for research which may someday contribute to improved clinical care of formerly deployed veterans of the Persian Gulf War.

Biological measures and diagnostic tools for Gulf War Illness - A systematic review

AIMS

Gulf War Illness (GWI) is a chronic multisymptom illness with debated etiology and pathophysiology. This systematic review catalogues studies of validated biological tests for diagnosing GWI and of associations between biological measures and GWI for their promise as biomarkers.

MAIN METHODS

We searched multiple sources through February 2020 for studies of diagnostic tests of GWI and of associations between biological measures and GWI. We abstracted data on study design, demographics, and outcomes. We assessed the risk of bias of included studies.

KEY FINDINGS

We did not identify any studies validating tests of biomarkers that distinguish cases of GWI from non-cases. We included the best-fitting studies, 32 completed and 24 ongoing or unpublished studies, of associations between GWI and biological measures. The less well-fitting studies (n = 77) were included in a Supplementary Table. Most studies were of the central nervous and immune systems and indicated a significant association of the biological measure with GWI case status. Biological measures were heterogeneous across studies.

SIGNIFICANCE

Our review indicates that there are no existing validated biological tests to determine GWI case status. Many studies have assessed the potential association between a variety of biological measures and GWI, the majority of which pertain to the immune and central nervous systems. More importantly, while most studies indicated a significant association between biological measures and GWI case status, the biological measures across studies were extremely heterogeneous. Due to the heterogeneity, the focus of the review is to map out what has been examined, rather than synthesize information.

Metabolic features of Gulf War illness

BACKGROUND

More than 230,000 veterans-about 1/3 of US personnel deployed in the 1990-1991 Persian Gulf War-developed chronic, multi-symptom health problems now called "Gulf War illness" (GWI), for which mechanisms and objective diagnostic signatures continue to be sought.

METHODS

Targeted, broad-spectrum serum metabolomics was used to gain insights into the biology of GWI. 40 male participants, included 20 veterans who met both Kansas and CDC diagnostic criteria for GWI and 20 nonveteran controls without similar symptoms that were 1:1 matched to GWI cases by age, sex, and ethnicity. Serum samples were collected and archived at -80° C prior to testing. 358 metabolites from 46 biochemical pathways were measured by hydrophilic interaction liquid chromatography and tandem mass spectrometry.

RESULTS

Veterans with GWI, compared to healthy controls, had abnormalities in 8 of 46 biochemical pathways interrogated. Lipid abnormalities accounted for 78% of the metabolic impact. Fifteen ceramides and sphingomyelins, and four phosphatidylcholine lipids were increased. Five of the 8 pathways were shared with the previously reported metabolic phenotype of males with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS). However, 4 of the 5 shared pathways were regulated in opposite directions; key pathways that were up-regulated in GWI were down-regulated in ME/CFS. The single pathway regulated in the same direction was purines, which were decreased.

CONCLUSIONS

Our data show that despite heterogeneous exposure histories, a metabolic phenotype of GWI was clearly distinguished from controls. Metabolomic differences between GWI and ME/CFS show that common clinical symptoms like fatigue can have different chemical mechanisms and different diagnostic implications. Larger studies will be needed to validate these findings.

Insomnia Severity, Subjective Sleep Quality, and Risk for Obstructive Sleep Apnea in Veterans With Gulf War Illness

Despite the fact that sleep disturbances are common in veterans with Gulf War Illness (GWI), there has been a paucity of published sleep studies in this veteran population to date. Therefore, the present study examined subjective sleep quality (assessed with the Pittsburgh Sleep Quality Index), insomnia severity (assessed with the Insomnia Severity Index), and risk for obstructive sleep apnea (assessed with the STOP questionnaire) in 98 Gulf War veterans. Veterans with GWI, defined either by the Kansas or Centers for Disease Control and Prevention criteria, had greater risk for obstructive sleep apnea (i.e., higher STOP scores) than veterans without GWI. This difference persisted even after accounting for potentially confounding demographic (e.g., age, gender) and clinical variables. Veterans with GWI, defined by either the Kansas or Centers for Disease Control and Prevention criteria, also had significantly greater insomnia severity and poorer sleep quality than veterans without GWI (p < 0.05), even after accounting for potentially confounding variables. Furthermore, there were significant, positive correlations between insomnia severity, subjective sleep quality, and GWI symptom severity (p ≤ 0.01). In stepwise linear regression models, insomnia severity significantly predicted GWI status over and above demographic and clinical variables. Together these findings provide good rationale for treating sleep disturbances in the management of GWI.

Somatic syndromes, insomnia, anxiety, and stress among sleep disordered breathing patients

OBJECTIVES

We tested the hypothesis that the prevalence of somatic syndromes, anxiety, and insomnia among sleep disordered breathing (SDB) patients is correlated with their levels of somatic arousal, the symptoms of increased sympathetic nervous system tone under conditions of stress.

METHODS

We administered the Body Sensation Questionnaire (BSQ; a 17-item questionnaire with increasing levels of somatic arousal scored 17-85) to 152 consecutive upper airway resistance syndrome (UARS) patients and 150 consecutive obstructive sleep apnea/hypopnea (OSA/H) patients. From medical records, we characterized each patient in terms of the presence of syndromes and symptoms into three categories: somatic syndromes (six syndromes), anxiety (anxiety disorders, nightmares, use of benzodiazepines), and insomnia (sleep onset, sleep maintenance, and use of hypnotics). For the pooled sample of SDB patients, we modeled the correlation of the BSQ score with the presence of each syndrome/symptom parameter within each of the three categories, with adjustment for male vs. female.

RESULTS

Mean BSQ scores in females were significantly higher than those in males (32.5 ± 11.1 vs. 26.9 ± 8.2; mean ± SD). Increasing BSQ scores significantly correlated with increasing prevalence rates of somatic syndromes (p < 0.0001), of anxiety (p < 0.0001), and of insomnia (p ≤ 0.0001). In general, females had higher prevalence rates of somatic syndromes and symptoms of anxiety than males at any BSQ score while rates of insomnia were similar.

CONCLUSIONS

In patients with SDB, there is a strong association between the level of somatic arousal and the presence of stress-related disorders like somatic syndromes, anxiety, and insomnia.

Somatic arousal and sleepiness/fatigue among patients with sleep-disordered breathing

OBJECTIVES

In a large clinical sample, we tested the hypothesis that levels of sleepiness and fatigue among upper airway resistance syndrome (UARS) patients are correlated with levels of somatic arousal (SA; reflecting the sympathetic nervous system component of the stress response). We also tested the correlations of post-treatment change in these three parameters, and we extended the investigation to obstructive sleep apnea/hypopnea (OSA/H) patients.

METHODS

From 5 years of patient data, we obtained scores on the body sensation questionnaire (BSQ), measuring the level of SA, the fatigue severity scale (FSS), and Epworth sleepiness scale (ESS) for 152 consecutive UARS patients and 150 consecutive OSA/H patients. For each group, we correlated the FSS and ESS scores with the BSQ scores. Among the 45 UARS patients and 49 OSA/H patients treated with nasal CPAP who provided post-treatment data, we correlated change in FSS and ESS scores with change in BSQ scores.

RESULTS

Scores on the BSQ, FSS, and ESS for UARS patients and OSA/H patients were comparable. In both UARS and OSA/H patients, both the FSS and ESS scores were positively correlated with the BSQ score. Nasal CPAP use decreased all three questionnaire scores in both patient groups. In the pooled data, changes in FSS were significantly correlated with changes in BSQ.

CONCLUSIONS

Our findings confirm our preliminary observations that sleepiness and fatigue among UARS patients are correlated with their level of SA and suggest that the same is true for OSA/H patients. The decrease of SA following treatment suggests that SDB is a cause of SA among patients with UARS and OSA/H.

The association of somatic arousal with the symptoms of upper airway resistance syndrome

OBJECTIVES

We tested the hypothesis that the symptoms of upper airway resistance syndrome (UARS) are manifestations of chronic stress. To accomplish this, we utilized the score on a self-report questionnaire for somatic arousal (a component of stress) to compare somatic arousal between UARS patients and healthy controls and, among all participants, to correlate the level of somatic arousal with the severity of UARS symptoms.

METHODS

We administered the Mood and Anxiety Symptom Questionnaire anxious arousal subscale (MASQaas; a 17-item questionnaire with increasing levels of arousal scored 17-85) to 12 UARS patients and 12 healthy controls and compared scores between groups. For all participants, we correlated the MASQaas scores with scores for the Epworth Sleepiness Scale (ESS), Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-Fatigue) scale, Pittsburgh Sleep Quality Index (PSQI), SF-36 Health Survey, and Perceived Deficits Questionnaire (PDQ; assessing cognitive function).

RESULTS

Compared to healthy controls, UARS patients demonstrated increased somatic arousal (MASQaas scores of 18±2 and 28±7, respectively; p<0.0001). For all participants, the MASQaas scores correlated significantly with scores of the ESS (r=0.64; p=0.0008), the FACIT-Fatigue scale (r=-0.89; p<0.0001), the PSQI (r=0.70; p=0.0002), SF-36 Physical component (r=-0.78; p<0.0001), SF-36 Mental component (r=-0.74; p<0.0001), and the PDQ (r=0.89; p<0.0001).

CONCLUSIONS

Our findings suggest that UARS patients have increased levels of the stress component, somatic arousal, proportionate to the severity of their symptoms.

Autoimmune/inflammatory syndrome induced by adjuvants (ASIA) 2013: Unveiling the pathogenic, clinical and diagnostic aspects

In 2011 a new syndrome termed 'ASIA Autoimmune/Inflammatory Syndrome Induced by Adjuvants' was defined pointing to summarize for the first time the spectrum of immune-mediated diseases triggered by an adjuvant stimulus such as chronic exposure to silicone, tetramethylpentadecane, pristane, aluminum and other adjuvants, as well as infectious components, that also may have an adjuvant effect. All these environmental factors have been found to induce autoimmunity by themselves both in animal models and in humans: for instance, silicone was associated with siliconosis, aluminum hydroxide with post-vaccination phenomena and macrophagic myofasciitis syndrome. Several mechanisms have been hypothesized to be involved in the onset of adjuvant-induced autoimmunity; a genetic favorable background plays a key role in the appearance on such vaccine-related diseases and also justifies the rarity of these phenomena. This paper will focus on protean facets which are part of ASIA, focusing on the roles and mechanisms of action of different adjuvants which lead to the autoimmune/inflammatory response. The data herein illustrate the critical role of environmental factors in the induction of autoimmunity. Indeed, it is the interplay of genetic susceptibility and environment that is the major player for the initiation of breach of tolerance.

A comparison of inspiratory airflow dynamics during sleep between upper airway resistance syndrome patients and healthy controls

OBJECTIVES

A test of the hypothesis that upper airway resistance syndrome (UARS) patients have an increased prevalence of inspiratory airflow limitation (IFL) during sleep compared to healthy controls.

METHODS

We compared inspiratory airflow dynamics during sleep between 12 UARS patients (nine females and three males) and 12 healthy controls matched for age, gender and obesity with maximal age limited at 45 years. A standard clinical polysomnogram (airflow measured with a nasal/oral pressure catheter) was performed to assess the impact of SDB on the participants' natural sleep. A second full-night polysomnogram with a pneumotachograph and a supraglottic pressure catheter to measure airflow and effort was performed to compare the maximal inspiratory airflow and effort and the percentage of flow-limited breaths during supine, continuous stage 2 sleep between groups.

RESULTS

During clinical polysomnography, UARS participants did not differ significantly from controls in sleep architecture or fragmentation. We observed a small difference in apnea hypopnea index between UARS participants and controls (1.6 ± 1.9 vs. 0.4 ± 0.3, respectively; p = 0.035). During supine, continuous stage 2 sleep, 64.2 % (35.8; mean (SD)) of UARS participants' breaths were flow-limited compared with 34.0 % (39.3) of controls' breaths (p = 0.06). The groups did not differ in maximal inspiratory airflow or inspiratory effort.

CONCLUSIONS

Our findings indicate a less-than-robust difference in respiratory parameters during sleep between UARS patients and healthy controls and no difference in standard sleep parameters or sleep fragmentation. We consider a pathophysiology of UARS that incorporates these findings.

Functional somatic syndromes, anxiety disorders and the upper airway: a matter of paradigms

The relationship between the functional somatic syndromes, anxiety disorders and the upper airway (particularly, sleep disordered breathing) remains ambiguous. This ambiguity, despite a growing body of research supporting a relationship, may result from the absence of a paradigm to explain how upper airway dysfunction can promote disorders commonly associated with one's mental health. This review models the functional somatic syndromes and anxiety disorders as consequences of chronically increased hypothalamic-pituitary-adrenal axis activity. It then examines the literature supporting a relationship between these disorders and upper airway dysfunction during wakefulness and sleep. Finally, building upon an existing paradigm of neural sensitization, sleep disordered breathing is linked to functional somatic syndromes and anxiety disorders through chronic activation of the hypothalamic-pituitary-adrenal axis.

The effect of nasal continuous positive airway pressure on the symptoms of Gulf War illness

PURPOSE

We performed a pilot study to determine whether nasal continuous positive airway pressure (CPAP) alleviates the symptoms of veterans with Gulf War illness (GWI) and sleep disordered breathing (SDB).

METHODS

Eighteen male veterans with GWI and SDB recruited by advertisement, participated in a randomized, single-masked, sham-controlled treatment trial. Participants received 3 weeks of treatment during sleep with either therapeutic nasal CPAP or sham nasal CPAP. Using validated questionnaires, pain, fatigue, cognitive function, sleep disturbance, and general health were assessed by self-report before and after treatment. One of the participants assigned to therapeutic CPAP was excluded from the trial before starting treatment, leaving 17 participants.

RESULTS

Compared to the nine sham nasal CPAP recipients, the eight participants receiving therapeutic nasal CPAP experienced improvements in pain (34%; p = 0.0008), fatigue (38%; p = 0.0002), cognitive function (33%; p = 0.004), sleep quality (41%; p = 0.0003), physical health (34%; p = 0.0003), and mental health (16%; p = 0.03).

CONCLUSIONS

Our findings in this pilot study suggest that nasal CPAP may greatly improve symptoms in veterans with GWI and SDB.