Co-occurring Chronic Pain and PTSD Among US Military Veterans: Prevalence, Correlates, and Functioning.

BACKGROUND: The prevalence of co-occurring chronic pain and posttraumatic stress disorder (PTSD) has yet to be established in a nationally representative sample of US veterans, and little is known about the individual contributing roles of these disorders to the psychiatric and functional burden of this comorbidity. OBJECTIVE: To determine the prevalence of chronic pain, PTSD, and co-occurring chronic pain and PTSD, and psychiatric comorbidities and psychosocial functioning in these groups. DESIGN: Data were analyzed from the National Health and Resilience in Veterans Study, which surveyed a nationally representative sample of US veterans. PARTICIPANTS: Veterans (n=4069) were classified into four groups: control (i.e., no PTSD or chronic pain), chronic pain only, PTSD only, and co-occurring chronic pain and PTSD. MAIN MEASURES: A probable PTSD diagnosis was established using the PTSD Checklist for DSM-5, and a chronic pain diagnosis using a self-report item that queried health care professional diagnoses. Psychiatric and functional status were assessed using the Patient Health Questionnaire-4, Alcohol Use Disorders Identification Test, Screen of Drug Use, Suicide Behaviors Questionnaire-Revised, Short Form Health Survey-8, Brief Inventory of Psychosocial Functioning, and Medical Outcomes Study Cognitive Functioning Scale. KEY RESULTS: A total of 3.8% of veterans reported both probable PTSD and a diagnosis of chronic pain. Relative to veterans with chronic pain alone, those with co-occurring chronic pain and probable PTSD were more likely to screen positive for psychiatric disorders (odds ratios [ORs]=2.59-9.88) and scored lower on measures of psychosocial functioning (Cohen's ds=0.38-1.43). Relative to veterans with probable PTSD only, those with co-occurring chronic pain and probable PTSD were more likely to have attempted suicide (OR=4.79; 95%CI, 1.81-12.69). CONCLUSIONS: Results underscore the importance of whole health care that considers a broad range of health and functional domains in the assessment and treatment of co-occurring chronic pain and PTSD in veterans.

Risk Factors Associated with Unsuccessful High-Resolution Manometry.

High-resolution manometry (HRM) is used to evaluate the esophageal motor function. Unfortunately, there are times when testing cannot be performed accurately. Our study aimed to quantify the occurrence of failed HRM and identify the associated risk factors. HRM tests were retrospectively collected between September 2021 and August 2022. HRM reports that could not be interpreted based on standard HRM protocol as per Chicago guidelines were classified as failed tests. Information reviewed included testing indications, patient demographics, previous medical/symptom history, and follow-up testing for failed HRM. We then compared patients with successful vs. unsuccessful HRM based on our pre-specified factors. 152 HRM tests were performed, of which 28 tests (18%) were unsuccessful. Factors associated with failed manometry included a history of nausea/vomiting, dyspepsia, and achalasia. Patients who were unable to tolerate the probe during testing were more likely to have a history of dyspepsia (OR 20.3, p = < 0.001) and/or nausea/vomiting (OR 13.8, p = < 0.001). A history of achalasia was found to have an odds ratio of 13.2 when examining failure because of curling of the manometry catheter (p = 0.012). All seven patients who had repeat HRM with endoscopic placement were successful in obtaining diagnostic information. There are two groups that have risk factors for unsuccessful HRM testing. A history of nausea/vomiting and dyspepsia symptoms were associated with being unable to tolerate the manometry probe. The second group comprises patients with a history of achalasia in whom probe curling is more common. Future research targeting these risk factors may minimize diagnostic and treatment delays.

Protease-Induced Excitation of Dorsal Root Ganglion Neurons in Response to Acute Perturbation of the Gut Microbiota Is Associated With Visceral and Somatic Hypersensitivity.

BACKGROUND & AIMS: Abdominal pain is a major symptom of diseases that are associated with microbial dysbiosis, including irritable bowel syndrome and inflammatory bowel disease. Germ-free mice are more prone to abdominal pain than conventionally housed mice, and reconstitution of the microbiota in germ-free mice reduces abdominal pain sensitivity. However, the mechanisms underlying microbial modulation of pain remain elusive. We hypothesized that disruption of the intestinal microbiota modulates the excitability of peripheral nociceptive neurons. METHODS: In vivo and in vitro assays of visceral sensation were performed on mice treated with the nonabsorbable antibiotic vancomycin (50 µg/mL in drinking water) for 7 days and water-treated control mice. Bacterial dysbiosis was verified by 16s rRNA analysis of stool microbial composition. RESULTS: Treatment of mice with vancomycin led to an increased sensitivity to colonic distension in vivo and in vitro and hyperexcitability of dorsal root ganglion (DRG) neurons in vitro, compared with controls. Interestingly, hyperexcitability of DRG neurons was not restricted to those that innervated the gut, suggesting a widespread effect of gut dysbiosis on peripheral pain circuits. Consistent with this, mice treated with vancomycin were more sensitive than control mice to thermal stimuli applied to hind paws. Incubation of DRG neurons from naive mice in serum from vancomycin-treated mice increased DRG neuron excitability, suggesting that microbial dysbiosis alters circulating mediators that influence nociception. The cysteine protease inhibitor E64 (30 nmol/L) and the protease-activated receptor 2 (PAR-2) antagonist GB-83 (10 µmol/L) each blocked the increase in DRG neuron excitability in response to serum from vancomycin-treated mice, as did the knockout of PAR-2 in NaV1.8-expressing neurons. Stool supernatant, but not colonic supernatant, from mice treated with vancomycin increased DRG neuron excitability via cysteine protease activation of PAR-2. CONCLUSIONS: Together, these data suggest that gut microbial dysbiosis alters pain sensitivity and identify cysteine proteases as a potential mediator of this effect.

The mediating role of posttraumatic stress disorder symptoms in pain cognitions among Veterans with chronic pain.

Symptoms of posttraumatic stress disorder (PTSD) are highly prevalent among Veterans with chronic pain. Considerable research has examined the intersection of chronic pain and PTSD symptoms. However, it remains unclear whether changes in PTSD may potentially serve a mechanistic role in improving unhelpful pain cognitions for individuals with chronic pain. The present research contributes to the foundational knowledge by addressing this question. Baseline data from a randomized controlled trial targeting pain-related disability for Veterans (n = 103; mean age 43.66; SD = 10.17) with musculoskeletal pain and depression and/or PTSD symptoms were used. Cross-sectional mediation analyses showed that PTSD symptoms mediated the relationship between pain severity and pain catastrophizing, and between pain severity and pain acceptance. After controlling for depression, the mediation involving pain catastrophizing remained significant, while the mediation for pain acceptance did not. Although limitations exist, results point to several treatment recommendations, including ensuring that depressive affect, PTSD-specific symptoms, and attention to both body and mind are included in treatment. Results also provide preliminary evidence for examining these associations longitudinally to improve our understanding of this population and corresponding treatment recommendations.

Expression and function of transient receptor potential melastatin 3 in the spinal afferent innervation of the mouse colon.

Abdominal pain is a cardinal symptom of inflammatory bowel disease (IBD). Transient receptor potential (TRP) channels contribute to abdominal pain in preclinical models of IBD, and TRP melastatin 3 (TRPM3) has recently been implicated in inflammatory bladder and joint pain in rodents. We hypothesized that TRPM3 is involved in colonic sensation and is sensitized during colitis. We used immunohistochemistry, ratiometric Ca2+ imaging, and colonic afferent nerve recordings in mice to evaluate TRPM3 protein expression in colon-projecting dorsal root ganglion (DRG) neurons, as well as functional activity in DRG neurons and colonic afferent nerves. Colitis was induced using dextran sulfate sodium (DSS) in drinking water. TRPM3 protein expression was observed in 76% of colon-projecting DRG neurons and was often colocalized with calcitonin gene-related peptide. The magnitudes of intracellular Ca2+ transients in DRG neurons in response to the TRPM3 agonists CIM-0216 and pregnenolone sulfate sodium were significantly greater in neurons from mice with colitis compared with controls. In addition, the percentage of DRG neurons from mice with colitis that responded to CIM-0216 was significantly increased. CIM-0216 also increased the firing rate of colonic afferent nerves from control and mice with colitis. The TRPM3 inhibitor isosakuranetin inhibited the mechanosensitive response to distension of wide dynamic range afferent nerve units from mice with colitis but had no effect in control mice. Thus, TRPM3 contributes to colonic sensory transduction and may be a potential target for treating pain in IBD.NEW & NOTEWORTHY This is the first study to characterize TRPM3 protein expression and function in colon-projecting DRG neurons. A TRPM3 agonist excited DRG neurons and colonic afferent nerves from healthy mice. TRPM3 agonist responses in DRG neurons were elevated during colitis. Inhibiting TRPM3 reduced the firing of wide dynamic range afferent nerves from mice with colitis but had no effect in control mice.

Comparable Minimally Important Differences and Responsiveness of Brief Pain Inventory and PEG Pain Scales across 6 Trials.

The 3-item pain intensity (P), interference with the enjoyment of life (E), and interference with general activity (G), or PEG, has become one of the most widely used measures of pain severity and interference. The minimally important differences (MID) and responsiveness of the PEG are essential metrics for solidifying its role in research and clinical care. The current study aims to establish the MID and responsiveness of the PEG by synthesizing data from 1,710 participants across 6 controlled trials. MIDs were estimated using absolute score changes among individuals reporting their pain was "a little better" on a retrospective global change anchor as well as distribution-based estimates using standard deviation thresholds and 1 and 2 standard errors of measurement. Responsiveness was assessed using standardized response means, area under the curve, and treatment effect sizes. MID estimates for the PEG ranged from 0.60 to 1.1 when using 0.35 SD, and 0.78 to 1.22 using 1 standard error of measurement. MID estimates using the global anchor had somewhat more variability but most estimates ranged from 1.0 to 1.75. Responsiveness effect sizes were generally large (>.80) for standardized response means and moderate (>.50) for treatment effect. Similarly, the most area under the curve values demonstrated an acceptable level of scale responsiveness (≥.70). Importantly, MID estimates and responsiveness of the PEG and BPI scales were largely comparable when aggregating data across trials. Our synthesis indicates that 1 point is a reasonable MID estimate on these 0- to 10-point pain scales, with 2 points being an upper bound. PERSPECTIVE: This article synthesizes data from 6 clinical trials to establish the minimally important difference (MID) and responsiveness of the 3-item PEG pain scale. The PEG demonstrated good responsiveness, and 1 to 2 points proved to be reasonable estimates for the lower and upper bounds of the MID.

Examining the Veterans Health Administration whole health model of care within the context of posttraumatic stress disorder.

The Veterans Health Administration's Whole Health system of care focuses on offering veterans holistic health approaches and tailoring health care to individual's goals and preferences. The present study assessed factors associated with Whole Health use and its potential benefits among veterans with posttraumatic stress disorder (PTSD) receiving Veterans Health Administration care. This cohort study used retrospective electronic health records combined with survey data (baseline, 6 months) from 18 Veterans Affairs Whole Health pilot implementation sites and compared patient-reported outcomes between veterans who used Whole Health services versus those who did not, among veterans with (n = 1,326) and without (n = 3,243) PTSD. Patient-reported outcomes assessed were pain (PEG), patient-reported outcomes measurement information system physical and mental health functioning, and a one-item global meaning and purpose assessment. Veterans with PTSD were more likely to have used Whole Health (38% vs. 21%) than those without PTSD. Veterans with PTSD who used Whole Health services experienced small improvements over 6 months in physical (Cohen's d = .12) and mental (Cohen's d = .15) health functioning. Veterans without PTSD who used Whole Health services experienced small improvements in physical health (Cohen's d = .09) but not mental health (Cohen's d = .04). Veterans with PTSD were frequently connected with Whole Health services even though implementation efforts were not explicitly focused on reaching this population. Results suggest Whole Health may play an important role in how veterans with PTSD engage with health care. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Introducing the integrated model of co-occurring chronic pain and posttraumatic stress disorder: Adding meaning-making and existential concepts to current theory.

OBJECTIVE: Making meaning out of the experience of chronic pain and posttraumatic stress disorder (PTSD) is a core process of recovery and symptom management of the comorbidity and a key active ingredient in the treatment for these conditions. Managing the effects of chronic pain and PTSD symptoms often evokes anxieties that could be considered existential (e.g., loss of meaning in life and concerns about one's identity). However, current theoretical models of co-occurring chronic pain and PTSD do not capture core meaning-making processes involved in either condition, resulting in the potential to overlook their centrality. The objective of the current work is to integrate current theoretical models of co-occurring chronic pain and PTSD with theory and science related to meaning-making and existential anxiety. METHOD: A targeted literature review was used to develop a novel model of co-occurring chronic pain and PTSD. RESULTS: The present work introduces the integrated model of co-occurring chronic pain and PTSD, which is a first attempt at integrating current theoretical perspectives of co-occurring chronic pain and PTSD with the literature on meaning-making and closely related existential perspectives. We outline model-specific hypotheses and describe model implications and future directions. CONCLUSIONS: The model provides clinicians and researchers with a more thorough conceptualization of how chronic pain and PTSD interact, which symptoms to target, and which outcomes may be important for individuals who have both chronic pain and PTSD. As a result, the model has the potential to improve pain and PTSD outcomes, and perhaps health outcomes more broadly, within this population. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Minimal important difference metrics and test-retest reliability of the PTSD Checklist for DSM-5 with a primary care sample.

The PTSD Checklist for DSM-5 (PCL-5) is a measure of posttraumatic stress disorder (PTSD) symptom severity that is widely used for clinical and research purposes. Although previous work has examined metrics of minimal important difference (MID) of the PCL-5 in veteran samples, no work has identified PCL-5 MID metrics among adults in primary care in the United States. In this secondary analysis, data were evaluated from primary care patients (N = 971) who screened positive for PTSD and participated in a large clinical trial in federally qualified health centers in three U.S. states. Participants primarily self-identified as women (70.2%) and White (70.3%). We calculated test-retest reliability using clinic registry data and multiple distribution- and anchor-based metrics of MID using baseline and follow-up survey data. Test-retest reliability (Pearson's r, Spearman's ρ, intraclass correlation coefficient) ranged from adequate to excellent (.79-.94), with the shortest time lag demonstrating the highest reliability estimate. The MID for the PCL-5 was estimated using multiple approaches. Distribution-based approaches indicated an MID range of 8.5-12.5, and anchor-based approaches indicated an MID range of 9.8-11.7. Taken together, the MID metrics indicate that PCL-5 change scores of 9-12 likely reflect real change in PTSD symptoms and indicate at least an MID for patients, whereas PCL-5 change scores of 5 or less likely are not reliable. These findings can help inform clinicians using the PCL-5 in similar populations to track patient responses to treatment and help researchers interpret PCL-5 score changes in clinical trials.

VHA Whole Health Services and Complementary and Integrative Health Therapies: a Gateway to Evidence-Based Mental Health Treatment.

BACKGROUND: Engagement in evidence-based psychotherapy (EBP) among veterans with behavioral health conditions is often low. The Veterans Health Administration (VHA) is implementing a "Whole Health (WH)" system of care, to identify veteran personal health goals, align care with those goals, and offer services designed to engage and empower veterans to achieve well-being. OBJECTIVE: To examine the relationship between veteran WH utilization and subsequent engagement in EBP. DESIGN: Retrospective analysis of VHA administrative records from 18 facilities implementing WH. SUBJECTS: Veterans (n = 265,364) with a diagnosis of depression, post-traumatic stress disorder (PTSD), and/or anxiety who had a mental healthcare encounter but no EBP use in fiscal year (FY) 2018. Among this cohort, 33,146 (12.5%) began using WH in FY2019. MAIN MEASURES: We examined use of an EBP for depression, anxiety, and/or PTSD within 1 year of the index date of WH use compared to use of an EBP anytime during FY2019 for veterans not identified as using WH. We used multiple logistic regression to examine the association between veteran WH use and EBP engagement. KEY RESULTS: Approximately 3.0% (n = 7,860) of the veterans in our overall cohort engaged in an EBP in the year following their index date. Controlling for key demographic, health, and utilization variables, WH users had 2.4 (95% CI: 2.2-2.5) times higher odds of engaging in an EBP the following year than those with no WH utilization. Associations between utilization of specific WH services (vs. no utilization of that service) and engagement in an EBP in the subsequent year ranged from 1.6 (95% CI: 1.0-2.6) to 3.5 (95% CI: 3.2-3.9) across the different types of WH services used. CONCLUSIONS: WH use was associated with increased engagement in EBPs among veterans with depression, anxiety, and/or PTSD. Future interventions intended to promote veteran engagement in EBPs may benefit from leveraging WH services and therapies.

Evolving acidic microenvironments during colitis provide selective analgesic targets for a pH-sensitive opioid.

ABSTRACT: Targeting the acidified inflammatory microenvironment with pH-sensitive opioids is a novel approach for managing visceral pain while mitigating side effects. The analgesic efficacy of pH-dependent opioids has not been studied during the evolution of inflammation, where fluctuating tissue pH and repeated therapeutic dosing could influence analgesia and side effects. Whether pH-dependent opioids can inhibit human nociceptors during extracellular acidification is unexplored. We studied the analgesic efficacy and side-effect profile of a pH-sensitive fentanyl analog, (±)- N -(3-fluoro-1-phenethylpiperidine-4-yl)- N -phenyl propionamide (NFEPP), during the evolution of colitis induced in mice with dextran sulphate sodium. Colitis was characterized by granulocyte infiltration, histological damage, and acidification of the mucosa and submucosa at sites of immune cell infiltration. Changes in nociception were determined by measuring visceromotor responses to noxious colorectal distension in conscious mice. Repeated doses of NFEPP inhibited nociception throughout the course of disease, with maximal efficacy at the peak of inflammation. Fentanyl was antinociceptive regardless of the stage of inflammation. Fentanyl inhibited gastrointestinal transit, blocked defaecation, and induced hypoxemia, whereas NFEPP had no such side effects. In proof-of-principle experiments, NFEPP inhibited mechanically provoked activation of human colonic nociceptors under acidic conditions mimicking the inflamed state. Thus, NFEPP provides analgesia throughout the evolution of colitis with maximal activity at peak inflammation. The actions of NFEPP are restricted to acidified layers of the colon, without common side effects in normal tissues. N -(3-fluoro-1-phenethylpiperidine-4-yl)- N -phenyl propionamide could provide safe and effective analgesia during acute colitis, such as flares of ulcerative colitis.

Dietary monosodium glutamate increases visceral hypersensitivity in a mouse model of visceral pain.

BACKGROUND: Monosodium glutamate (MSG) has been identified as a trigger of abdominal pain in irritable bowel syndrome (IBS), but the mechanism is unknown. This study examined whether MSG causes visceral hypersensitivity using a water-avoidance stress (WAS) mouse model of visceral pain. METHODS: Mice were divided into four groups receiving treatment for 6 days: WAS + MSG gavage, WAS + saline gavage, sham-WAS + MSG gavage, and sham-WAS + saline gavage. The acute effects of intraluminal administration of 10 µM MSG on jejunal extrinsic afferent nerve sensitivity to distension (0-60 mmHg) were examined using ex vivo extracellular recordings. MSG was also applied directly to jejunal afferents from untreated mice. Glutamate concentration was measured in serum, and in the serosal compartment of Ussing chambers following apical administration. KEY RESULTS: Acute intraluminal MSG application increased distension responses of jejunal afferent nerves from mice exposed to WAS + MSG. This effect was mediated by wide dynamic range and high-threshold units at both physiologic and noxious pressures (10-60 mmHg, p < 0.05). No effect of MSG was observed in the other groups, or when applied directly to the jejunal afferent nerves. Serum glutamate was increased in mice exposed to WAS + MSG compared to sham-WAS + saline, and serosal glutamate increased using WAS tissue (p = 0.0433). CONCLUSIONS AND INFERENCES: These findings demonstrate that repeated exposure to MSG in mice leads to sensitization of jejunal afferent nerves to acute ex vivo exposure to MSG. This may contribute to visceral hypersensitivity reported in response to MSG in patients with IBS.

Utilization of Whole Health and Longitudinal Outcomes After Screening Positive for Possible Depression Documented in Veterans Health Administration's Electronic Health Record.

Objectives: Depression is common among Veterans. Veterans Health Administration (VHA) is transforming into a Whole Health system of care that includes holistic treatment planning, well-being programs, and health coaching. This evaluation explores the impact of Whole Health on improving symptoms of depression among Veterans who screen positive for possible depression diagnosis. Materials and Methods: We examined a cohort of Veterans who started using Whole Health after screening positive for possible depression (having a PHQ-2 score ≥3) at 18 VA Whole Health sites. We compared Whole Health users with non-Whole Health users on their follow-up PHQ-2 scores (9-36 months after baseline), using propensity score matching with multivariable regression to adjust for baseline differences. Results: Of the 13,559 Veterans screening positive for possible depression on the PHQ-2 and having a follow-up PHQ-2, 902 (7%) began using Whole Health after their initial positive PHQ-2. Whole Health users at baseline were more likely than non-Whole Health users to have posttraumatic stress disorder or acute stress (43% vs. 29%), anxiety (22% vs. 12%), ongoing opioid use (14% vs. 8%), recent severe pain scores (15% vs. 8%), or obesity (51% vs. 40%). Both groups improved at follow-up, with mean PHQ-2 scores decreasing from 4.49 to 1.77 in the Whole Health group and 4.46 to 1.46 in the conventional care group, with the Whole Health group significantly higher at follow-up. Also, the proportion continuing to screen positive at follow-up trended higher in the Whole Health group (26% and 21%, respectively). Conclusions: After screening positive for depression, Veterans with more mental and physical health conditions were more likely to subsequently use Whole Health services, suggesting that Whole Health is becoming a tool used in VHA to address the needs of complex patients. Nevertheless, the Whole Health group did not improve compared to the Conventional Care group. Results add to the growing body of literature that Whole Health services may play an important role among patients with complex symptom presentations by promoting self-management of symptoms and targeting "what matters most" to Veterans.

Bark beetle impacts on forest evapotranspiration and its partitioning.

Insect outbreaks affect forest structure and function and represent a major category of forest disturbance globally. However, the resulting impacts on evapotranspiration (ET), and especially hydrological partitioning between the abiotic (evaporation) and biotic (transpiration) components of total ET, are not well constrained. As a result, we combined remote sensing, eddy covariance, and hydrological modeling approaches to determine the effects of bark beetle outbreak on ET and its partitioning at multiple scales throughout the Southern Rocky Mountain Ecoregion (SRME), USA. At the eddy covariance measurement scale, 85 % of the forest was affected by beetles, and water year ET as a fraction of precipitation (P) decreased by 30 % relative to a control site, with 31 % greater reductions in growing season transpiration relative to total ET. At the ecoregion scale, satellite remote sensing masked to areas of >80 % tree mortality showed corresponding ET/P reductions of 9-15 % that occurred 6-8 years post-disturbance, and indicated that the majority of the total reduction occurred during the growing season; the Variable Infiltration Capacity hydrological model showed an associated 9-18 % increase in the ecoregion runoff ratio. Long-term (16-18 year) ET and vegetation mortality datasets extend the length of previously published analyses and allowed for clear characterization of the forest recovery period. During that time, transpiration recovery outpaced total ET recovery, which was lagged in part due to persistently reduced winter sublimation, and there was associated evidence of increasing late summer vegetation moisture stress. Overall, comparison of three independent methods and two partitioning approaches demonstrated a net negative impact of bark beetles on ET, and a relatively greater negative impact on transpiration, following bark beetle outbreak in the SRME.

Analysis of the spinal and vagal afferent innervation of the mouse colon using neuronal retrograde tracers.

The gut-brain axis has received increasing attention recently due to evidence that colonic microbes can affect brain function and behavior. However, little is known about the innervation of the colon by a major component of the gut-brain axis, vagal afferent neurons. Furthermore, it is currently unknown whether individual NG neurons or DRG neurons innervate both the proximal and distal colon. We aimed to quantify the number of vagal and spinal afferent neurons that innervate the colon; and determine whether these individual neurons simultaneously innervate the mouse proximal and distal colon. C57Bl/6 mice received injections of a combination of retrograde tracers that were either injected into the muscularis externa of the proximal or the distal colon: fast blue, DiI and DiO. Five to seven percent of lumbosacral and thoracolumbar spinal afferent neurons, and 25% of vagal afferent neurons were labelled by injections of DiI and DiO into the colon. We also found that approximately 8% of NG neurons innervate the distal colon. Ten percent of labeled thoracolumbar and 15% of labeled lumbosacral DRG neurons innervate both the distal and proximal colon. Eighteen percent of labeled NG neurons innervated both the distal and proximal colon. In conclusion, vagal afferent innervation of the distal colon is less extensive than the proximal colon, whereas a similar gradient was not observed for the spinal afferent innervation. Furthermore, overlap appears to exist between the receptive fields of vagal and spinal afferent neurons that innervate the proximal and distal colon.

Mechanisms of change in posttraumatic headache-related disability: A mediation model.

OBJECTIVE: To explore whether the association between change in headache management self-efficacy and posttraumatic headache-related disability is partially mediated by a change in anxiety symptom severity. BACKGROUND: Many cognitive-behavioral therapy treatments for headache emphasize stress management, which includes anxiety management strategies; however, little is currently known about mechanisms of change in posttraumatic headache-related disability. Increasing our understanding of mechanisms could lead to improvements in treatments for these debilitating headaches. METHODS: This study is a secondary analysis of veterans (N = 193) recruited to participate in a randomized clinical trial of cognitive-behavioral therapy, cognitive processing therapy, or treatment as usual for persistent posttraumatic headache. The direct relationship between headache management self-efficacy and headache-related disability, along with partial mediation through change in anxiety symptoms was tested. RESULTS: The mediated latent change direct, mediated, and total pathways were statistically significant. The path analysis supported a significant direct pathway between headache management self-efficacy and headache-related disability (b = -0.45, p < 0.001; 95% confidence interval [CI: -0.58, -0.33]). The total effect of change of headache management self-efficacy scores on change in Headache Impact Test-6 scores was significant with a moderate-to-strong effect (b = -0.57, p = 0.001; 95% CI [-0.73, -0.41]). There was also an indirect effect through anxiety symptom severity change (b = -0.12, p = 0.003; 95% CI [-0.20, -0.04]). CONCLUSIONS: In this study, most of the improvements in headache-related disability were related to increased headache management self-efficacy with mediation occurring through change in anxiety. This indicates that headache management self-efficacy is a likely mechanism of change of posttraumatic headache-related disability with decreases in anxiety explaining part of the improvement in headache-related disability.

A Comparison of Psychosocial Services for Enhancing Cultural Adaptation and Global Functioning for Immigrant Survivors of Torture.

Forced migrants suffer from significant psychological distress. However, they often prioritize urgent practical resettlement needs over mental health needs. The present study used a quasi-experimental design to compare pathways of treatment for survivors of torture (N = 369) from 42 different counties receiving care from a refugee health clinic. Random intercept ANOVAs were used to compare combined case management services and psychological treatment (CM-PT) to case management services only (CM) on changes in cultural adaptation and global functioning over time. Results showed that both groups improved on each outcome. Importantly, the CM-PT group endorsed greater improvements in cultural adaptation (b = 0.28, 95% CI 0.14, 0.41, p ≤ 0.001) and global functioning (b = 3.29, 95% CI 1.33, 5.25, p = 0.001) compared to the CM group. These findings suggest that treatment for survivors of torture should be multifaceted and include case management and psychological treatment. Case management services alone may be beneficial when socio-cultural and resource barriers exist for mental health treatment.

Diet-microbial cross-talk underlying increased visceral perception.

Visceral hypersensitivity, a fundamental mechanism of chronic visceral pain disorders, can result from both central or peripheral factors, or their combination. As an important regulator of normal gut function, the gut microbiota has been implicated as a key peripheral factor in the pathophysiology of visceral hypersensitivity. Patients with chronic gastrointestinal disorders, such as irritable bowel syndrome, often present with abdominal pain secondary to adverse reactions to dietary components. As both long- and short-term diets are major determinants of gut microbiota configuration that can result in changes in microbial metabolic output, it is becoming increasingly recognized that diet-microbiota interactions play an important role in the genesis of visceral sensitivity. Changes in pain signaling may occur via diet-induced changes in secretion of mediators by both the microbiota and/or host cells. This review will examine the peripheral influence of diet-microbiota interactions underlying increased visceral sensitivity.

Histamine production by the gut microbiota induces visceral hyperalgesia through histamine 4 receptor signaling in mice.

The gut microbiota has been implicated in chronic pain disorders, including irritable bowel syndrome (IBS), yet specific pathophysiological mechanisms remain unclear. We showed that decreasing intake of fermentable carbohydrates improved abdominal pain in patients with IBS, and this was accompanied by changes in the gut microbiota and decreased urinary histamine concentrations. Here, we used germ-free mice colonized with fecal microbiota from patients with IBS to investigate the role of gut bacteria and the neuroactive mediator histamine in visceral hypersensitivity. Germ-free mice colonized with the fecal microbiota of patients with IBS who had high but not low urinary histamine developed visceral hyperalgesia and mast cell activation. When these mice were fed a diet with reduced fermentable carbohydrates, the animals showed a decrease in visceral hypersensitivity and mast cell accumulation in the colon. We observed that the fecal microbiota from patients with IBS with high but not low urinary histamine produced large amounts of histamine in vitro. We identified Klebsiella aerogenes, carrying a histidine decarboxylase gene variant, as a major producer of this histamine. This bacterial strain was highly abundant in the fecal microbiota of three independent cohorts of patients with IBS compared with healthy individuals. Pharmacological blockade of the histamine 4 receptor in vivo inhibited visceral hypersensitivity and decreased mast cell accumulation in the colon of germ-free mice colonized with the high histamine-producing IBS fecal microbiota. These results suggest that therapeutic strategies directed against bacterial histamine could help treat visceral hyperalgesia in a subset of patients with IBS with chronic abdominal pain.