Exploring relationships for visceral and somatic pain with autonomic control and personality

Personality traits related to cognitive functioning in patients with functional neurological disorder

Cognitive symptoms are prevalent in patients with functional neurological disorder (FND). Several studies have suggested that personality traits such as neuroticism may play a pivotal role in the development of FND. FND has also been associated with alexithymia: patients with FND report difficulties in identifying, analyzing, and verbalizing emotions. Whether or not alexithymia and other personality traits are associated with cognitive symptomatology in patients with FND is unknown. In the current study, we explored whether the Big Five personality model factors (neuroticism, extraversion, openness, agreeableness, and conscientiousness) and alexithymia were associated with cognitive functioning in FND. Twenty-three patients with FND were assessed using a neuropsychological assessment and questionnaire assessment to explore personality traits (Neuroticism-Extraversion-Openness Five-Factor Inventory) and alexithymia (Bermond-Vorst Alexithymia Questionnaire). The results indicated that high conscientiousness was associated with lower planning scores (ρ = -0.52, p = .012) and high scores on alexithymia were associated with lower scores on verbal memory scores (ρ = -0.46, p = .032) and lower sustained attention scores (ρ = -0.45, p = .046). The results did not remain significant after controlling for multiple testing. The preliminary results of our study suggest that personality and cognitive symptomatology in patients with FND are topics that should be further explored in future studies, as cognitive symptomology can affect treatment results.

Pain Recognition in Ferrets

Recognition and accurate assessment of the severity of pain can be challenging in ferrets as they are unable to verbally communicate, and often hide their pain. Pain assessment relies on the assessment of behavioral, physiologic, and other clinical parameters that serve as indirect indicators of pain. Assessment of physiologic and clinical parameters requires handling, which results in changes in these parameters. Behavioral parameters can be assessed less invasively by observing the patient. Due to their nonspecificity, correct interpretation may be challenging. Just as in other species, a grimace scale seems to be the most helpful tool in recognizing pain in ferrets.

Personality construct as a biomarker in fibromyalgia: A narrative review from an autonomic rehabilitation perspective

BACKGROUND

The heterogeneity of symptoms and ineffective treatment raise questions about the current diagnostic criteria of fibromyalgia (FM). Misdiagnosis of FM often leads to less than efficacious treatment and poor quality of life.

OBJECTIVE

This article reviews relevant evidence-based literature on personality traits in FM patients with an autonomic dysfunction perspective based on a hierarchical model to explain the utility of considering the personality trait in FM diagnosis.

METHODS

A narrative review of articles concerning chronic pain, FM, and personality traits with respect to autonomic dysfunction in FM was conducted after extensive relevant literature searches.

RESULTS

Reports discussing the predisposing factors, including coping styles, anger, suicide risk, a lack of physical activity and social support, in maintaining persistent pain in FM exist. Relationships between pain duration and severity and personality traits like neuroticism and extraversion have been reported. Coexisting clinical manifestations of FM like sleep disorders, anxiety, and intestinal irritability indicate autonomic dysfunction.

CONCLUSIONS

This article lays out a constructive framework for individualized and personalized medicine for the effective rehabilitation of FM patients. The quest to find a definitive diagnosis of FM should include personality biomarkers that might translate into personalized medicine. An individualistic approach may bank upon artificial intelligence algorithms for both diagnostic as well as prognostic purposes in FM.

Motor Learning in Response to Different Experimental Pain Models Among Healthy Individuals: A Systematic Review

Learning new movement patterns is a normal part of daily life, but of critical importance in both sport and rehabilitation. A major question is how different sensory signals are integrated together to give rise to motor adaptation and learning. More specifically, there is growing evidence that pain can give rise to alterations in the learning process. Despite a number of studies investigating the role of pain on the learning process, there is still no systematic review to summarize and critically assess investigations regarding this topic in the literature. Here in this systematic review, we summarize and critically evaluate studies that examined the influence of experimental pain on motor learning. Seventeen studies that exclusively assessed the effect of experimental pain models on motor learning among healthy human individuals were included for this systematic review, carried out based on the preferred reporting items for systematic reviews and meta-analyses (PRISMA) statement. The results of the review revealed there is no consensus regarding the effect of pain on the skill learning acquisition and retention. However, several studies demonstrated that participants who experienced pain continued to express a changed motor strategy to perform a motor task even 1 week after training under the pain condition. The results highlight a need for further studies in this area of research, and specifically to investigate whether pain has different effects on motor learning depending on the type of motor task.

An investigation into the effect of nasogastric intubation on markers of autonomic nervous function

BACKGROUND

Nasogastric (NG) intubation for esophageal manometry can be traumatic and may be associated with a temporary reduction/absence in esophageal peristalsis. This study explored the prevalence and effect on esophageal motor function. We also hypothesized that baseline anxiety as well as markers of autonomic nerve function were correlated to attenuated esophageal peristalsis.

METHODS

Twenty-seven patients with esophageal symptoms referred for esophageal manometry investigation (mean age 56.8 ± 16.7 years, range 23-85 years) reported baseline anxiety score (Likert scale) preintubation. Patients had continuous heart rate and blood pressure measured prior to intubation and until 10 min after catheter withdrawal. Quality of motility was assessed for each 5 ml water swallow using standard Chicago Classification metrics.

KEY RESULTS

Nasogastric-intubation elicited a significant increase in heart rate (p < 0.001), systolic (p < 0.001) and diastolic (p < 0.001) blood pressure, which was in part anticipatory. The median time taken for patients' first hypotensive peristalsis (Distal Contractile Integral; DCI ≥100 mmHg s cm) was 130 s (Interquartile range; 47-242 s) and for their first normal peristalsis (DCI ≥450 mm Hg s cm) was 150 s (IQR 61-320 s), with improvement and consistent stabilization in DCI there onward. This corresponded closely to the time for initial recovery of heart rate and systolic and diastolic blood pressure postintubation.

CONCLUSIONS AND INFERENCES

Nasogastric intubation resulted in heightened sympathetic responses and/or dampened parasympathetic responses, and an associated temporary reduction or absence in esophageal peristalsis.

Heart Rate Variability and Pain: A Systematic Review

Background and Objective: Heart rate variability (HRV) as an index of the autonomic nervous system appears to be related to reactivity to experimental pain stimuli. HRV could better explain the contributions of sympathetic and parasympathetic activity response to nociceptive stimulation. The aim of this study was to systematically review and synthesize the current evidence on HRV in relation to the experience of pain in experimental tasks. Databases and Data Treatment: Studies indexed in the PubMed, PsycINFO, MEDLINE, WebOfScience, and Scopus databases were reviewed for eligibility. Studies on the autonomic response (i.e., HRV) to experimentally induced pain in healthy adults were included. Different methods of pain induction were considered (e.g., thermal, pressure, and electrical). Data were synthesized considering the association between HRV and both pain induction and subjective measures of pain. Results: Seventy-one studies were included. The results underline significant change in both the sympathetic and parasympathetic autonomic nervous systems during the painful stimulation independent of the pain induction method. The autonomic reaction to pain could be affected by several factors, such as sex, age, body mass index, breathing patterns, the intensity of the stimulation, and the affective state. Moreover, an association between the autonomic nervous system and the subjective experience of pain was found. Higher parasympathetic activity was associated with better self-regulation capacities and, accordingly, a higher pain inhibition capacity. Conclusions: HRV appears to be a helpful marker to evaluate nociceptive response in experimentally induced pain. Future studies are also needed in clinical samples to understand better the interindividual changes of autonomic response due to pain stimuli.

More Insight on the Role of Personality Traits and Sensitivity to Experimental Pain

Purpose

The present study aimed to assess the influence of personality traits on the variability of sensitivity to pain in two distinct groups of healthy subjects with low versus high sensitivity to pain (LSP vs HSP, respectively).

Methods

Healthy subjects (n=156) were allocated to two groups according to their tolerability to cold stimulation (cold pressor test, CPT, 1°C). Group LSP (n=76) reached the cut-off time of 180±0 sec, and a size matched group of HSP (n=80) tolerated the CPT for an average of 10.5±3.4 sec only. Subjects from both groups completed the self-reported pain sensitivity questionnaire (PSQ), the Pain Catastrophizing Scale (PCS), and the Neuroticism Extraversion Openness - Five Factor Inventory (NEO-FFI).

Results

In comparison to the LSP group, HSP individuals had higher scores of PSQ (p<0.001), catastrophizing (p=0.001), and extraversion (p=0.01). By adjusting for age and gender, mediation analyses revealed that catastrophizing mediated the relationship between neuroticism and pain sensitivity, both in the allocation of subjects to a certain group of sensitivity to pain (LSP or HSP, B=0.02 95% CI: 0.006–0.040) and in the PSQ score (B=0.01 95% CI: 0.001–0.023).

Conclusion

These results, which were demonstrated by two different prisms (CPT and PSQ), point to the potential of the five-factor inventory and pain catastrophizing scale as tools for identifying specific personality traits associated with a high sensitivity to pain.

The relationship between personality traits and psychosomatic complaints in a sample of Iranian adults

BACKGROUND

It has been suggested that personality traits may be related to the psychological conditions of people. The current study aimed to explore the relationship between personality traits and psychosomatic complaints.

METHODS

This study was carried out on a sample of Iranian adults living in Isfahan province. The NEO Five- Factor Inventory questionnaire was used to assess personality traits. A 30-item comprehensive questionnaire was used to assess somatoform symptoms and factor analysis was performed to construct psychosomatic complaints profiles. Data was analyzed by Multiple Indicators Multiple Causes (MIMIC) model, using R software.

RESULTS

In total, 4763 participants were recruited 44.2% males and 55.8% females, with a mean age of 36.54 ± 8.04 years. The results of the MIMIC model showed that there is a significant association between the dimensions of personality (neuroticism, extroversion, openness, agreeableness and conscientiousness) and dimensions of psychosomatic complaints profiles (gastrointestinal, neuro-skeletal, pharyngeal-respiratory and psychological) (P < 0.05). In addition, we found that characteristics such as age, sex, marital status, education, physical activity, and body mass index are related to psychosomatic complaints (P < 0.05) and can affect the association between personality traits and psychosomatic complaints.

CONCLUSIONS

Given the relationship between personality traits and psychosomatic complaints, it is possible to provide preventive and therapeutic interventions for psychosomatic complaints based on personality traits specific to each individual.

Multi-sensory Responsiveness and Personality Traits Predict Daily Pain Sensitivity

Background: A continuous effort has been devoted to identifying factors that contribute to individual differences in pain perception. Amongst the personality traits, Neuroticism is assumed to be the most significant moderator of experimental and clinical pain. Multi-sensory responsiveness to daily sensations has been shown to be associated with pain perception. Yet, neither the relationship between personality traits and multi-sensory responsiveness nor the impact of both these factors to pain perception have been examined. Thus, this study aims to explore the contribution of both multi-sensory responsiveness and personality traits to pain perception in a daily context.

Methods: A community-based sample of 204 adults completed the Sensory Responsiveness Questionnaire-Intensity Scale (SRQ-IS); the Big Five Inventory (BFI); and the Pain Sensitivity Questionnaire (PSQ).

Results: The partial eta-square demonstrated that the SRQ-IS Aversive sub-scale score had the strongest relationship with the PSQ-Total score, accounting for 9% of the variation. The regression coefficient relating PSQ-Total score with SRQ-IS Aversive, and BFI sub-scales of Extraversion, Neuroticism and Openness-to-Experience scores was found to be r = 0.39 (p < 0.0001), accounting for 16% of the variance, and yielding a large effect size.

Discussion: To the best of our knowledge this is the first study to report on the interplay between aversive responsiveness to daily sensations and personality traits of Neuroticism, Openness-to-Experience, and Extraversion as contributing factors to daily pain sensitivity, amongst which aversive responsiveness was found as the major contributing factor. This study may broaden the understanding of the pain experience variability, both in practice and in experimental research.

Distinguishing pain from nociception, salience, and arousal: How autonomic nervous system activity can improve neuroimaging tests of specificity

Pain is a subjective, multidimensional experience that is distinct from nociception. A large body of work has focused on whether pain processing is supported by specific, dedicated brain circuits. Despite advances in human neuroscience and neuroimaging analysis, dissociating acute pain from other sensations has been challenging since both pain and non-pain stimuli evoke salience and arousal responses throughout the body and in overlapping brain circuits. In this review, we discuss these challenges and propose that brain-body interactions in pain can be leveraged in order to improve tests for pain specificity. We review brain and bodily responses to pain and nociception and extant efforts toward identifying pain-specific brain networks. We propose that autonomic nervous system activity should be used as a surrogate measure of salience and arousal to improve these efforts and enable researchers to parse out pain-specific responses in the brain, and demonstrate the feasibility of this approach using example fMRI data from a thermal pain paradigm. This new approach will improve the accuracy and specificity of functional neuroimaging analyses and help to overcome current difficulties in assessing pain specific responses in the human brain.

Cardio-respiratory autonomic responses to nociceptive stimuli in patients with disorders of consciousness

The autonomic response to pain might discriminate among consciousness disorders. Therefore, aim of this study was to describe differences between minimally conscious state (MCS) and unresponsive wakefulness syndrome (UWS) patients in their autonomic response to a nociceptive stimulus. ECG, respiration, finger blood pressure (BP) and total peripheral resistances (TPR) were continuously recorded before, during and after a standardized noxious stimulus in 20 adult brain-injured patients, 14 in UWS and 6 in MCS. Occurrence of fast autonomic responses synchronous with the stimulus was detected by visual inspection of the tracings; short-term (<20 s) and long-term (between 20s and 50 s from the stimulus) responses were evaluated by beat-by-beat quantitative analysis. The noxious stimulus elicited fast responses in both groups, but only MCS patients showed a significant short-term response in TPR and long-term response in HR. Thus, short- and long-term cardiovascular responses to pain might integrate neuro-behavioural assessments to discriminate between MCS and UWS.

Preliminary report: parasympathetic tone links to functional brain networks during the anticipation and experience of visceral pain

The mechanisms that underpin the anti-nociceptive effect of the parasympathetic nervous system (PNS) on visceral pain remain incompletely understood. We sought to describe the effect of resting parasympathetic tone on functional brain networks during the anticipation and experience of oesophageal pain. 21 healthy participants had their resting cardiac vagal tone (CVT), a validated measure of the PNS, quantified, and underwent functional magnetic resonance imaging during the anticipation and experience of painful oesophageal distention. The relationship between resting CVT and functional brain networks was examined using 11 hypothesis-driven nodes and network-based statistics. A network comprising all nodes was apparent in individuals with high resting CVT, compared to those with low CVT, during oesophageal pain (family wise error rate (FWER)-corrected p < 0.048). Functional connections included the thalamus-amygdala, thalamus-hypothalamus, hypothalamus-nucleus accumbens, amygdala-pallidum, pallidum-nucleus accumbens and insula-pallidum. A smaller network was seen during pain anticipation, comprising the amygdala, pallidum and anterior insula (FWER-corrected p < 0.049). These findings suggest that PNS tone is associated with functional brain networks during the anticipation and experience of visceral pain. Given the role of these subcortical regions in the descending inhibitory modulation of pain, these networks may represent a potential neurobiological explanation for the anti-nociceptive effect of the PNS.

HYPNOTIZABILITY AND PAIN MODULATION: A Body-Mind Perspective

The study investigated whether the cardiac activity and cognitive-emotional traits sustained by the behavioral inhibition/activation system (BIS/BAS) may contribute to hypnotizability-related pain modulation. Nociceptive stimulation (cold-pressor test) was administered to healthy participants with high (highs) and low (lows) hypnotizability in the presence and absence of suggestions for analgesia. Results showed that heart rate increased abruptly at the beginning of nociceptive stimulation in all participants. Then, only in highs heart rate decreased for the entire duration of hand immersion. During stimulation with suggestions of analgesia, pain threshold negatively correlated with heart rate. BIS/BAS activity partially accounted for the observed hypnotizability-related differences in the relation between cardiac interoception and pain experience.

Investigating the use of pre-training measures of autonomic regulation for assessing functional overreaching in endurance athletes

The use of heart rate variability (HRV) to inform daily training prescription is becoming common in endurance sport. Few studies, however, have investigated the use of pre-training HRV to predict decreased performance or altered exercising autonomic response, typical of functional overreaching (FOR). Further, a new cardiac vagal tone (ProCVT) technology purports to eliminate some of the noise associated with daily HRV, and therefore may be better at predicting same-day performance. The purpose of this investigation was to examine if changes to resting HRV and ProCVT were associated with alterations in performance, maximal heart rate (HRmax), or heart rate recovery (HRrec) in FOR athletes. Twenty-eight recreational cyclists and triathletes were assigned to experimental/control conditions and underwent: 1 week of reduced training, 3 weeks of overload (OL) or regular training (CON), and 1 week of recovery. Testing occurred following the reduced training week (T1), post-3 weeks of training (T2), and following the recovery week (T3). Measures of resting HRV/ProCVT were collected each testing session, followed by maximal incremental exercise tests with HRrec taken 60 s post-exercise. Performance decreased from T1 to T2 in the OL group vs. CON (Δ-9 ± 12 vs. Δ9 ± 11 W, P < .001), as did HRmax (Δ-8 ± 4 vs. Δ-2 ± 4 bpm, P < .001). HRrec increased from T1 to T2 in the OL group vs. CON (Δ10 ± 9 vs. Δ2 ± 5 beats/min, P < .01). HRV and ProCVT did not change in either group. Same-day resting autonomic measures are insufficient in predicting alterations to performance or exercising HR measures following overload training.

[Psychophysiology of visceral pain]

The psychophysiology of visceral pain is--different from cardiac psychophysiology--much less well investigated due to the invasiveness of its methods and problems associated with reliably and reproducibly stimulating as well as recording of the gastrointestinal tract. Despite these problems, the last 30 years have documented a number of psychophysiological phenomena such as the perception (interoception) of visceral stimuli, the effect of emotions and stress on visceral sensations, and the effect of visceral processes on cortical processing. This was mainly due to the application of neurophysiological techniques (cortical imaging and stimulation) in these investigations.

Preliminary report: modulation of parasympathetic nervous system tone influences oesophageal pain hypersensitivity

OBJECTIVES

Autonomic nervous system dysfunction has been implicated in visceral hypersensitivity. However, the specific contribution of the parasympathetic nervous system (PNS) is unclear. We aimed to determine whether physiological and pharmacological manipulation of parasympathetic tone influences the development of hypersensitivity in a validated model of acid-induced oesophageal pain.

DESIGN

Prior to, and following, a 30-min distal oesophageal infusion of 0.15 M hydrochloric acid, pain thresholds to electrical stimulation were determined in the proximal non-acid exposed oesophagus in healthy subjects. Validated sympathetic (skin conductance response) and parasympathetic (cardiac vagal tone) parameters were measured at baseline and continuously thereafter. In study 1, 55 subjects were randomised in a pragmatic blinded crossover design to receive deep breathing or un-paced breathing during acid infusion. In study 2, 32 subjects were randomised in a blinded, crossover design to receive intravenous atropine or placebo (saline) with deep breathing during acid infusion.

RESULTS

Study 1: Deep breathing increased cardiac vagal tone (2.1±2.3 vs -0.3±2.3, p=0.0006) with concomitant withdrawal of skin conductance response (-0.6±4.9 vs 3±4.8, p=0.03) in comparison with un-paced breathing. Deep breathing prevented the development of acid-induced oesophageal hypersensitivity in comparison with sham breathing (p=0.0001). Study 2: Atropine, in comparison with placebo, blocked the attenuating effect of deep breathing on the development of acid-induced oesophageal hypersensitivity (p=0.046).

CONCLUSIONS

The development of oesophageal hyperalgesia is prevented by physiologically increasing parasympathetic tone. This effect is pharmacologically blocked with atropine, providing evidence that the PNS influences the development of oesophageal pain hypersensitivity.

Dynamic interactions between plasma IL-1 family cytokines and central endogenous opioid neurotransmitter function in humans

Evidence in animal models suggests IL-1 family cytokines interact with central endogenous opioid neurotransmitter systems, inducing or perpetuating pathological states such as persistent pain syndromes, depression, substance use disorders, and their comorbidity. Understanding these interactions in humans is particularly relevant to understanding pathological states wherein this neurotransmitter system is implicated (ie, persistent pain, mood disorders, substance use disorders, etc). Here, we examined relationships between IL-1β, IL-1ra, and functional measures of the endogenous opioid system in 34 healthy volunteers, in the absence and presence of a standardized sustained muscular pain challenge, a psychophysical challenge with emotionally and physically stressful components. Mu-opioid receptor availability in vivo was examined with [(11)C]carfentanil positron emission tomography (PET) scanning. Sex and neuroticism impacted IL-1 family cytokines; higher baseline IL-1β and IL-1ra was identified in females with lower neuroticism. Higher baseline IL-1β was also associated with reduced μ-opioid receptor availability (amygdala) and greater pain sensitivity. The pain challenge increased IL-1β in females with high neuroticism. Strong associations between IL-1ra (an anti-nociceptive cytokine) and μ-opioid receptor activation (VP/NAcc) were identified during the pain challenge and the resulting analgesic effect of μ-opioid receptor activation was moderated by changes in IL-1β whereby volunteers with greater pain induced increase in IL-1β experienced less endogenous opioid analgesia. This study demonstrates the presence of relationships between inflammatory factors and a specific central neurotransmitter system and circuitry, of relevance to understanding interindividual variations in regulation of responses to pain and other physical and emotional stressors.

Safety of a novel formulation of ibuprofen sodium compared with standard ibuprofen and placebo

BACKGROUND

Ibuprofen (IBU) is an efficacious over-the-counter analgesic/antipyretic with adverse event (AE) rates comparable to placebo. IBU sodium (IBU(Na)) is a newer, more soluble form that is absorbed faster than standard IBU, leading to more rapid analgesia. Although its safety and tolerability are expected to be comparable to standard IBU, this has not yet been reported.

METHODS

Pooled analysis comparing the safety of single-dose IBU(Na) (512 mg; equivalent to 400 mg IBU free acid; n = 362) with standard IBU tablets (400 mg; n = 342) and placebo (n = 187) across five Phase III, randomized, placebo-controlled, double-blind studies evaluating IBU(Na) for treatment of postoperative dental pain, tension-type headache, or fever.

RESULTS

Treatment-emergent AEs (TEAEs) occurred in 5% of cases in the IBU(Na) group (25 events), 6.4% of cases in the standard IBU group (41 events), and 10.2% of cases in the placebo group (31 events). The most frequent TEAEs were in the following Medical Dictionary for Regulatory Activities (MedDRA) System Organ Classes: gastrointestinal disorders (2.8, 3.2, and 5.9% for IBU(Na), standard IBU, and placebo, respectively), nervous system disorders (1.4, 3.5, and 3.7% for IBU(Na), standard IBU, and placebo, respectively), and general disorders and administration-site conditions (1.1, 1.5, and 2.1% for IBU(Na), standard IBU, and placebo, respectively). Nausea was the most common TEAE (2.5, 2.6, and 5.9% for IBU(Na), standard IBU, and placebo, respectively). Only two AEs were considered related to treatment: pruritus (n = 1, IBU(Na)) and nausea (n = 1, placebo). Of those subjects reporting ≥ 1 TEAE, 44.4, 36.4, and 89.5% of subjects in the IBU(Na), standard IBU, and placebo groups, respectively, received rescue medication.

CONCLUSION

IBU(Na) has a favorable safety profile comparable to those of standard IBU tablets and placebo in single-dose studies evaluating analgesic or antipyretic efficacy. ClinicalTrials.gov Registry Numbers: Dental pain studies: NCT01098747 and NCT01216163; headache studies: NCT01077973 and NCT01362491; pyresis study: NCT01035346.

Mechanisms of behavior modification in clinical behavioral medicine in China

BACKGROUND

Behavior modification, as the core of clinical behavioral medicine, is often used in clinical settings.

PURPOSE

We seek to summarize behavior modification techniques that are commonly used in clinical practice of behavioral medicine in China and discuss possible biobehavioral mechanisms.

METHODS

We reviewed common behavior modification techniques in clinical settings in China, and we reviewed studies that explored possible biobehavioral mechanisms.

RESULTS

Commonly used clinical approaches of behavior modification in China include behavior therapy, cognitive therapy, cognitive-behavioral therapy, health education, behavior management, behavioral relaxation training, stress management intervention, desensitization therapy, biofeedback therapy, and music therapy. These techniques have been applied in the clinical treatment of a variety of diseases, such as chronic diseases, psychosomatic diseases, and psychological disorders. The biobehavioral mechanisms of these techniques involve the autonomic nervous system, neuroendocrine system, neurobiochemistry, and neuroplasticity.

CONCLUSION

Behavior modification techniques are commonly used in the treatment of a variety of somatic and psychological disorders in China. Multiple biobehavioral mechanisms are involved in successful behavior modification.

Non-pharmacological Intervention for Chronic Pain in Veterans: A Pilot Study of Heart Rate Variability Biofeedback

OBJECTIVE

Chronic pain is an emotionally and physically debilitating form of pain that activates the body's stress response and over time can result in lowered heart rate variability (HRV) power, which is associated with reduced resiliency and lower self-regulatory capacity. This pilot project was intended to determine the effectiveness of HRV coherence biofeedback (HRVCB) as a pain and stress management intervention for veterans with chronic pain and to estimate the effect sizes. It was hypothesized that HRVCB will increase parasympathetic activity resulting in higher HRV coherence measured as power and decrease self-reported pain symptoms in chronic pain patients.

STUDY DESIGN

Fourteen veterans receiving treatment for chronic pain were enrolled in the pre-post intervention study. They were randomly assigned, with 8 subjects enrolled in the treatment group and 6 in the control group. The treatment group received biofeedback intervention plus standard care, and the other group received standard care only. The treatment group received four HRVCB training sessions as the intervention.

MEASURES

Pre-post measurements of HRV amplitude, HRV power spectrum variables, cardiac coherence, and self-ratings of perceived pain, stress, negative emotions, and physical activity limitation were made for both treatment and control groups.

RESULTS

The mean pain severity for all subjects at baseline, using the self-scored Brief Pain Inventory (BPI), was 26.71 (SD=4.46; range=21-35) indicating a moderate to severe perceived pain level across the study subjects. There was no significant difference between the treatment and control groups at baseline on any of the measures. Post-HRVCB, the treatment group was significantly higher on coherence (P=.01) and lower (P=.02) on pain ratings than the control group. The treatment group showed marked and statistically significant (1-tailed) increases over the baseline in coherence ratio (191%, P=.04) and marked, significant (1-tailed) reduction in pain ratings (36%, P<.001), stress perception (16%, P=.02), negative emotions (49%, P<.001), and physical activity limitation (42%, P<.001). Significant between-group effects on all measures were found when pre-training values were used as covariates.

CONCLUSIONS

HRVCB intervention was effective in increasing HRV coherence measured as power in the upper range of the LF band and reduced perceived pain, stress, negative emotions, and physical activity limitation in veterans suffering from chronic pain. HRVCB shows promise as an effective non-pharmacological intervention to support standard treatments for chronic pain.

Gastric and lower esophageal sphincter pressures during nausea: a study using visual motion-induced nausea and high-resolution manometry

Nausea is the subjective unpleasant sensation that immediately precedes vomiting. Studies using barostats suggest that gastric fundus and lower esophageal sphincter (LES) relaxation precede vomiting. Unlike barostat, high-resolution manometry allows less invasive, detailed measurements of fundus pressure (FP) and axial movement of the gastroesophageal junction (GEJ). Nausea was induced in 12 healthy volunteers by a motion video and rated on a visual analog scale. FP was measured as the mean value of the five pressure channels that were clearly positioned below the LES. After intubation, a baseline (BL) recording of 15 min was obtained. This was followed by presentation of the motion video (at least 10 min, maximum 20 min) followed by 30 min recovery recording. Throughout the experiment we recorded autonomic nervous system (ANS) parameters [blood pressure, heart rate (HR), and cardiac vagal tone (CVT), which reflects efferent vagal activity]. Ten out of 12 subjects showed a drop in FP during peak nausea compared with BL (-4.0 ± 0.8 mmHg; P = 0.005), and 8/10 subjects showed a drop in LES pressure (-8.8 ± 2.5 mmHg; P = 0.04). Peak nausea preceded peak fundus and LES pressure drop. Nausea was associated with configuration changes at the GEJ such as LES shortening and esophageal lengthening. During nausea we observed a significantly increased HR and decreased CVT. In conclusion, nausea is associated with a drop in fundus and LES pressure, configuration changes at the GEJ as well as changes in the ANS activity such as an increased sympathetic tone (increased HR) and decreased parasympathetic tone (decreased CVT).

Mechanisms of visceral pain in health and functional gastrointestinal disorders

Background and aims Chronic visceral pain is common both in patients with identifiable organic disease and also in those without any structural, biochemical or immunological abnormality such as in the functional gastrointestinal disorders (FGIDs). We aim to provide a contemporaneous summary of pathways involved in visceral nociception and how a variety of mechanisms may influence an individual's experience of visceral pain. Methods In this narrative review, we have brought together evidence through a detailed search of Medline in addition to using our experience and exposure to recent research developments from ourselves and other research groups. Results FGIDs are a heterogeneous group of disorders whose aetiology largely remains an enigma. The germane hypothesis for the genesis and maintenance of chronic visceral pain in FGIDs is the concept of visceral hypersensitivity. A number of peripheral and central mechanisms have been proposed to account for this epiphenomenon. In the periphery, inflammatory mediators activate and sensitize nociceptive afferent nerves by reducing their transduction thresholds and by inducing the expression and recruitment of hitherto silent nociceptors culminating in an increase in pain sensitivity at the site of injury known as primary hyperalgesia. Centrally, secondary hyperalgesia, defined as an increase in pain sensitivity in anatomically distinct sites, occurs at the level of the spinal dorsal horn. Moreover, the stress responsive physiological systems, genetic and psychological factors may modulate the experience of visceral pain. We also address some novel aetiological concepts in FGIDs, namely the gastrointestinal microbiota, connective tissue abnormalities and the gastrointestinal neuromuscular disorders. Firstly, the gastrointestinal microbiota is a diverse and dynamic ecosystem, that safeguards the host from external pathogens, aids in the metabolism of polysaccharides and lipids, modulates intestinal motility, in addition to modulating visceral perception. Secondly, connective tissue disorders, which traditionally have been considered to be confined largely to the musculoskeletal system, have an increasing evidence base demonstrating the presence of visceral manifestations. Since the sensorimotor apparatus of the GI tract is embedded within connective tissue it should not be surprising that such disorder may result in visceral pain and abnormal gut motility. Thirdly, gastrointestinal neuromuscular diseases refer to a heterogeneous group of disorders in which symptoms arise from impaired GI motor activity often manifesting as abnormal transit with or without radiological evidence of transient or persistent dilation of the viscera. Although a number of these are readily recognizable, such as achalasia or Hirschsprung's disease, the cause in a number of patients is not. An international working group has recently addressed this "gap", providing a comprehensive morphologically based diagnostic criteria. Conclusions/implications Although marked advances have been made in understanding the mechanisms that contribute to the development and maintenance of visceral pain, many interventions have failed to produce tangible improvement in patient outcomes. In the last part of this review we highlight an emerging approach that has allowed the definition and delineation of temporally stable visceral pain clusters, which may improve participant homogeneity in future studies, potentially facilitate stratification of treatment in FGID and lead to improvements in diagnostic criteria and outcomes.

Psychophysiological responses to visceral and somatic pain in functional chest pain identify clinically relevant pain clusters

BACKGROUND

Despite chronic pain being a feature of functional chest pain (FCP) its experience is variable. The factors responsible for this variability remain unresolved. We aimed to address these knowledge gaps, hypothesizing that the psychophysiological profiles of FCP patients will be distinct from healthy subjects.

METHODS

20 Rome III defined FCP patients (nine males, mean age 38.7 years, range 28-59 years) and 20 healthy age-, sex-, and ethnicity-matched controls (nine males, mean 38.2 years, range 24-49) had anxiety, depression, and personality traits measured. Subjects had sympathetic and parasympathetic nervous system parameters measured at baseline and continuously thereafter. Subjects received standardized somatic (nail bed pressure) and visceral (esophageal balloon distension) stimuli to pain tolerance. Venous blood was sampled for cortisol at baseline, post somatic pain and post visceral pain.

KEY RESULTS

Patients had higher neuroticism, state and trait anxiety, and depression scores but lower extroversion scores vs controls (all p < 0.005). Patients tolerated less somatic (p < 0.0001) and visceral stimulus (p = 0.009) and had a higher cortisol at baseline, and following pain (all p < 0.001). At baseline, patients had a higher sympathetic tone (p = 0.04), whereas in response to pain they increased their parasympathetic tone (p ≤ 0.008). The amalgamating the data, we identified two psychophysiologically distinct 'pain clusters'. Patients were overrepresented in the cluster characterized by high neuroticism, trait anxiety, baseline cortisol, pain hypersensitivity, and parasympathetic response to pain (all p < 0.03).

CONCLUSIONS & INFERENCES

In future, such delineations in FCP populations may facilitate individualization of treatment based on psychophysiological profiling.

Psychological traits influence autonomic nervous system recovery following esophageal intubation in health and functional chest pain

BACKGROUND

Esophageal intubation is a widely utilized technique for a diverse array of physiological studies, activating a complex physiological response mediated, in part, by the autonomic nervous system (ANS). In order to determine the optimal time period after intubation when physiological observations should be recorded, it is important to know the duration of, and factors that influence, this ANS response, in both health and disease.

METHODS

Fifty healthy subjects (27 males, median age 31.9 years, range 20-53 years) and 20 patients with Rome III defined functional chest pain (nine male, median age of 38.7 years, range 28-59 years) had personality traits and anxiety measured. Subjects had heart rate (HR), blood pressure (BP), sympathetic (cardiac sympathetic index, CSI), and parasympathetic nervous system (cardiac vagal tone, CVT) parameters measured at baseline and in response to per nasum intubation with an esophageal catheter. CSI/CVT recovery was measured following esophageal intubation.

KEY RESULTS

In all subjects, esophageal intubation caused an elevation in HR, BP, CSI, and skin conductance response (SCR; all p < 0.0001) but concomitant CVT and cardiac sensitivity to the baroreflex (CSB) withdrawal (all p < 0.04). Multiple linear regression analysis demonstrated that longer CVT recovery times were independently associated with higher neuroticism (p < 0.001). Patients had prolonged CSI and CVT recovery times in comparison to healthy subjects (112.5 s vs 46.5 s, p = 0.0001 and 549 s vs 223.5 s, p = 0.0001, respectively).

CONCLUSIONS & INFERENCES

Esophageal intubation activates a flight/flight ANS response. Future studies should allow for at least 10 min of recovery time. Consideration should be given to psychological traits and disease status as these can influence recovery.

Disposition and adjustment to chronic pain

Several empirical studies have shown that personal characteristics act as differential variables, which determine how pain is experienced and how the chronic pain patient adjusts to pain. The main aim of the present research is to review the relationships between some dispositional characteristics and pain adjustment. Taking into account the empirical literature, 6 personality traits that are relevant to the pain experience have been selected: neuroticism, anxiety sensitivity, and experiential avoidance as risk factors that increase the probability of patients experiencing a disability; and extraversion, optimism, and resilience as personal resources that increase their capacity to manage pain effectively. The results suggest that it would be useful to include an assessment of normal personality structure during the multi-dimensional evaluation of a person with chronic pain. Understanding these individual personality characteristics will aid in designing pain intervention programs and help predict possible treatment outcomes.

Gender, variation in opioid receptor genes and sensitivity to experimental pain

Background

Pain tolerance is subject to considerable inter-individual variation, which may be influenced by a number of genetic and non-genetic factors. The mu, delta and kappa opioid receptors play a role in pain perception and are thought to mediate different pain modalities. The aim of this study was to explore associations between pain thresholds and gender and genetic variants in the three opioid receptor genes (OPRM, OPRD and OPRK). Experimental multi-modal pain data from previously published studies carried out in healthy Caucasian volunteers were used in order to limit the number of confounders to the study outcome. Data on thermal skin pain (n=36), muscle pressure pain (n=31) and mechanical visceral pain (n=50)) tolerance thresholds were included.

Results

Nineteen genetic polymorphisms were included in linear regression modeling. Males were found to tolerate higher thermal and muscle pressure pain than females (p=0.003 and 0.02). Thirty four percent of variability in thermal skin pain was accounted for by a model consisting of OPRK rs6473799 and gender. This finding was just outside significance when correction for multiple testing was applied. Variability in muscle pressure pain tolerance was associated with OPRK rs7016778 and rs7824175. These SNPs accounted for 43% of variability in muscle pressure pain sensitivity and these findings remained significant after adjustment for multiple testing. No association was found with mechanical visceral pain.

Conclusion

This is a preliminary and hypothesis generating study due to the relatively small study size. However, significant association between the opioid receptor genes and experimental pain sensitivity supports the influence of genetic variability in pain perception. These findings may be used to generate hypotheses for testing in larger clinical trials of patients with painful conditions.

Ultra-marathon runners are different: investigations into pain tolerance and personality traits of participants of the TransEurope FootRace 2009

INTRODUCTION

Susceptibility to pain varies among individuals and may predispose to a higher risk for pain disorders. Thus, it is of interest to investigate subjects who exhibit higher resistance to pain. We therefore tested pain tolerance and assessed personality traits of ultra-marathon athletes who are able to run 4487 km (2789 mi) over 64 days without resting days and compare the results to controls.

METHODS

After approval of the local ethics committee and with informed consent, 11 participants of the TransEurope FootRace (TEFR09 participants) and 11 matched (age, sex, and ethnicity) controls without marathon experience in the last 5 years were enrolled. They were tested for cold pain tolerance (cold pressor [CP] test), and the 240 item trait and character inventory (TCI) as well as the general self-efficacy (GSE) test were obtained.

RESULTS

TransEurope FootRace participants had a highly significant greater cold pain tolerance in the CP test than controls (P = 0.0002). While the GSE test showed no differences, the TCI test provided TEFR09 participants to be less cooperative and reward dependent but more spiritually transcendent than the controls. Significant positive correlations were found between the CP test pain score at 180 seconds and several TCI subscales showing that higher pain scores correlate with higher reward dependence, dependence, cooperativeness, empathy, and pure-hearted conscience.

CONCLUSIONS

Personality profiles as well as pain tolerance of our sample of TEFR09 participants differ from normal controls and-as obtained in previous studies-probably also from chronic pain patients. Low pain perception may predispose a person to become a long-distance runner. It remains unclear, however, whether low pain perception is cause or consequence of continuous extreme training.

Five-factor personality traits and pain sensitivity: a twin study

Factors underlying individual differences in pain responding are incompletely understood, but are likely to include genetic influences on basal pain sensitivity in addition to demographic characteristics such as age, sex, and ethnicity, and psychological factors including personality. This study sought to explore the relationship between personality traits and experimental pain sensitivity, and to determine to what extent the covariances between these phenotypes are mediated by common genetic and environmental factors. A sample composed of 188 twins, aged 23 to 35years, was included in the study. Heat pain intensity (HPI) and cold-pressor pain intensity (CPI) ratings were obtained using standardized pain testing procedures, and personality traits were assessed with the NEO Personality Inventory, Revised. Associations between personality and the pain sensitivity indices were examined using zero-order correlations and generalized estimating equations. Bivariate Cholesky models were used in the biometric analyses. The most robust finding was a significant phenotypic association between CPI and the personality facets Impulsiveness (a facet of Neuroticism) and Excitement-Seeking (a facet of Extraversion), and estimates of the genetic correlation were .37 (P<.05) and .43 (P<.05), respectively. In contrast, associations between HPI and personality seemed weak and unstable, but a significant effect of Angry Hostility (a facet of Neuroticism) emerged in generalized estimating equations analysis. Although the genetic correlation between these phenotypes was essentially zero, a weak but significant individual-specific environmental correlation emerged (re=.21, P<.05). Taken together, these findings suggest that CPI is more consistently related to personality dispositions than HPI, both phenotypically and genetically.

The autonomic response to human esophageal acidification and the development of hyperalgesia

BACKGROUND

Distal esophageal acidification induces variable hyperalgesia in the non-acid exposed proximal esophagus. As the autonomic nervous system (ANS) modulates nociception, the aim was to determine whether autonomic reactivity to acid infusion predicted inter-individual differences in hyperalgesia.

METHODS

In 25 healthy volunteers (18 women, age range 22-58, mean 36.5 years), using a double-blind, placebo-controlled crossover design, pain thresholds to electrical stimulation were determined in the proximal esophagus and foot (control) pre and post a 30-min distal esophageal infusion of 0.15 mol L(-1) HCl or saline with autonomic monitoring. Sympathetic Cardiac Sympathetic Index and Skin Conductance Response and parasympathetic Cardiac Vagal Tone and Cardiac Sensitivity to Baroreflex measures were derived. Plasma cortisol was measured pre and post infusion as were anxiety and unpleasantness.

KEY RESULTS

Acid infusion reduced group pain threshold in the proximal esophagus (adjusted mean change -5.0 mA vs saline +3.4 mA, P < 0.001), and raised sympathetic measures (Cardiac Sympathetic Index, Skin Conduction Response) and cortisol levels, but reduced parasympathetic measures (cardiac vagal tone and cardiac sensitivity to Baroreflex) (all P < 0.05). Acid infusion also increased anxiety and unpleasantness scores (both P < 0.05). In 16 acid-sensitizers, the degree of hyperalgesia correlated with increasing heart rate (r = -0.66, P = 0.005), and fall in cardiac vagal tone (r = 0.54, P = 0.03) and Cardiac Sensitivity to Baroreflex (r = 0.54, P = 0.03).

CONCLUSIONS & INFERENCES

Acid-induced esophageal hyperalgesia correlated with reduced parasympathetic tone, suggesting that the parasympathetic nervous system may have anti hyperalgesic properties. Additional studies on the autonomic modulation of esophageal hyperalgesia are required.

Effects of skin-to-skin contact on autonomic pain responses in preterm infants

The purpose of this randomized crossover trial was to determine the effects on autonomic responses in preterm infants of longer Kangaroo Care (30 minutes, KC30) and shorter KC (15 minutes, KC15) before and throughout heel stick compared with incubator care (IC). Beat-to-beat heart rate (HR) and spectral power analysis of heart rate variability, low frequency power (LF), high frequency power (HF), and LF/HF ratio were measured in 26 infants. HR changes from Baseline to Heel Stick were significantly less in KC30 and KC15 than in IC, and more infants had HR decrease in IC than in 2 KC conditions. In IC, LF and HF significantly increased from Baseline to Heel Stick and dropped from Heel Stick to Recovery; in 2 KC conditions, no changes across study phases were found. During Heel Stick, LF and HF were significantly higher in IC than in KC30. In all 3 conditions, LF/HF ratio decreased from Baseline to Heel Stick and increased to Recovery; no differences were found between IC and two KC conditions. Both longer and shorter KC before and throughout heel stick can stabilize HR response in preterm infants, and longer KC significantly affected infants' sympathetic and parasympathetic responses during heel stick compared with incubator care.

PERSPECTIVE

This study showed that KC has a significant effect on reducing autonomic pain responses in preterm infants. The findings support that KC is a safe and effective pain intervention in the neonatal intensive care unit.

Neuroticism in young women with fibromyalgia links to key clinical features

Objective. We examined personality traits in young women with FM, in order to seek associations with key psychological processes and clinical symptoms. Methods. Twenty-seven women with FM and 29 age-matched female healthy controls [HC] completed a series of questionnaires examining FM symptoms, personality and psychological variables. Results. Significant differences between characteristic FM symptoms (sleep, pain, fatigue, and confusion) as well as for the psychological variables of depression, anxiety, and stress were found between FM and HC (P < 0.001). Neuroticism was the only subscale of the Big Five Inventory that showed a significant difference between the FM group and HC group [P < 0.05]. Within the FM group, there was a significant association between the level of the neuroticism and each of pain, sleep, fatigue, and confusion, depression, anxiety, and stress (P < 0.05–0.01). The association between the level of neuroticism and the level of stress was the strongest of all variables tested (P < 0.001). Conclusion. The personality trait of neuroticism significantly associates with the key FM characteristics of pain, sleep, fatigue and confusion as well as the common co-morbidities of depression, anxiety and stress. Personality appears to be an important modulator of FM clinical symptoms.

Agreeable smellers and sensitive neurotics--correlations among personality traits and sensory thresholds

Correlations between personality traits and a wide range of sensory thresholds were examined. Participants (N = 124) completed a personality inventory (NEO-FFI) and underwent assessment of olfactory, trigeminal, tactile and gustatory detection thresholds, as well as examination of trigeminal and tactile pain thresholds. Significantly enhanced odor sensitivity in socially agreeable people, significantly enhanced trigeminal sensitivity in neurotic subjects, and a tendency for enhanced pain tolerance in highly conscientious participants was revealed. It is postulated that varied sensory processing may influence an individual's perception of the environment; particularly their perception of socially relevant or potentially dangerous stimuli and thus, varied with personality.

Anterior insula integrates information about salience into perceptual decisions about pain

The decision as to whether a sensation is perceived as painful does not only depend on sensory input but also on the significance of the stimulus. Here, we show that the degree to which an impending stimulus is interpreted as threatening biases perceptual decisions about pain and that this bias toward pain manifests before stimulus encounter. Using functional magnetic resonance imaging we investigated the neural mechanisms underlying the influence of an experimental manipulation of threat on the perception of laser stimuli as painful. In a near-threshold pain detection paradigm, physically identical stimuli were applied under the participants' assumption that the stimulation is entirely safe (low threat) or potentially harmful (high threat). As hypothesized, significantly more stimuli were rated as painful in the high threat condition. This context-dependent classification of a stimulus as painful was predicted by the prestimulus signal level in the anterior insula, suggesting that this structure integrates information about the significance of a stimulus into the decision about pain. The anticipation of pain increased the prestimulus functional connectivity between the anterior insula and the midcingulate cortex (MCC), a region that was significantly more active during stimulation the more a participant was biased to rate the stimulation as painful under high threat. These findings provide evidence that the anterior insula and MCC as a "salience network" integrate information about the significance of an impending stimulation into perceptual decision-making in the context of pain.

Anxiety increases acid-induced esophageal hyperalgesia

OBJECTIVE

Anxiety at the time of gastrointestinal injury or inflammation increases the risk of developing visceral hyperalgesia. Distal esophageal acidification induces hyperalgesia in the non-acid exposed proximal esophagus, due to the sensitization of spinal dorsal horn neurones. The objective was to determine whether anxiety influences acid-induced hyperalgesia.

METHODS

A total of 19 healthy volunteers (n = 12 females; age, 22-57 years; mean, 35.7 years) completed a 10-minute mood induction paradigm (anxiety or neutral) with autonomic monitoring (visit 1). On visits 2 and 3, pain thresholds to electrical stimulation, in milliamperes (mA), were determined in the proximal esophagus and foot (control) before and after a 30-minute infusion of 0.15 M of hydrochloric acid. During esophageal acid infusion, the subjects randomly received anxiety or neutral mood induction with autonomic monitoring, in a crossover design. Anxiety and pain ratings were recorded pre and post infusion.

RESULTS

Visit 1: Anxiety induction increased anxiety scores (p < .001), mean arterial pressure (p < .001), and cardiac sympathetic index (p = .007), and reduced parasympathetic measures (cardiac vagal tone [p = .05] and cardiac sensitivity to baroreflex [p = .006)]). Visit 2: Anxiety induction conferred greater acid-induced hyperalgesia compared with neutral (-4.9 mA versus 2.7 mA, p = .009, analysis of covariance). No differences in autonomic measures were found during acid infusion with anxiety or neutral mood induction.

CONCLUSIONS

Anxiety induction increases acid-induced esophageal hyperalgesia; anxiety, thus, facilitates central sensitization in the esophagus. Our studies provide a new model for studying the effects of anxiety on esophageal hyperalgesia and may allow testing of therapeutic strategies to reduce this effect.

Conscious perception of errors and its relation to the anterior insula

To detect erroneous action outcomes is necessary for flexible adjustments and therefore a prerequisite of adaptive, goal-directed behavior. While performance monitoring has been studied intensively over two decades and a vast amount of knowledge on its functional neuroanatomy has been gathered, much less is known about conscious error perception, often referred to as error awareness. Here, we review and discuss the conditions under which error awareness occurs, its neural correlates and underlying functional neuroanatomy. We focus specifically on the anterior insula, which has been shown to be (a) reliably activated during performance monitoring and (b) modulated by error awareness. Anterior insular activity appears to be closely related to autonomic responses associated with consciously perceived errors, although the causality and directions of these relationships still needs to be unraveled. We discuss the role of the anterior insula in generating versus perceiving autonomic responses and as a key player in balancing effortful task-related and resting-state activity. We suggest that errors elicit reactions highly reminiscent of an orienting response and may thus induce the autonomic arousal needed to recruit the required mental and physical resources. We discuss the role of norepinephrine activity in eliciting sufficiently strong central and autonomic nervous responses enabling the necessary adaptation as well as conscious error perception.

The future of neuroscientific research in functional gastrointestinal disorders: integration towards multidimensional (visceral) pain endophenotypes?

The growing evidence for a key role of psychophysiological processes in the etiopathogenesis of functional gastrointestinal disorders (FGID) originates from various sources, including epidemiological, psychometric, physiological, and behavioural studies. Functional neuroimaging has improved our knowledge about central processing of visceral pain, a defining feature of FGID. However, results have been disappointingly inconsistent, often due to psychosocial factors not being controlled for. In this paper, we aim to show that using integrated research strategies, encompassing a number of scientific disciplines, is critical to advancing our understanding of FGID. We will illustrate this by describing recent integrative studies that may serve as good examples. More specifically, future FGID neuroimaging studies should control for psychosocial factors and incorporate methods from other branches of neuroscience outside this field, especially cognitive, affective and autonomic neuroscience. We therefore propose a framework for the development of an integrative cross-disciplinary research strategy based on advancing our understanding of visceral nociceptive physiology in health as well as vulnerability and susceptibility factors for FGID. This approach will allow the identification of factors responsible for the inter-individual differences in visceral pain perception and susceptibility to chronic visceral pain, leading to the description of multidimensional (visceral) pain "endophenotypes." These may represent the critical steps needed towards a pathophysiological, rather than symptom-based, classification of FGID, which may be more suitable for genetic association studies. This approach may ultimately culminate in individual tailoring of treatment, in addition to disease prevention, thereby improving outcomes for the patient and researcher alike.