Irritable bowel syndrome and symptom severity: evidence of negative attention bias, diminished vigour, and autonomic dysregulation

Attention in irritable bowel syndrome: A systematic review of affected domains and brain-gut axis interactions

BACKGROUND

Irritable bowel syndrome (IBS) is a disorder characterized by gut-brain interactions, leading to abdominal pain and altered stool patterns, which significantly affect patients' quality of life. Recent research suggests that attention may be impaired in individuals with IBS, potentially influencing symptom perception and emotional distress.

OBJECTIVE

This systematic review aims to examine the relationship between attention and IBS, focusing on the affected domains of attention and the interactions within the brain-gut axis.

METHODS

A comprehensive search was conducted across MEDLINE/PubMed, PsychINFO, and Scopus from January 1990 to December 2024. Studies included were those that assessed attention in adult IBS patients using valid measurement tools. A total of 24 studies were analyzed, incorporating neuroimaging and behavioral methods.

RESULTS

IBS individuals exhibit specific attentional impairments, including deficits in sustained attention, selective attentional biases toward gastrointestinal (GI)-related and symptom-specific stimuli, and heightened vigilance to threat and pain cues. Neurofunctional studies reveal altered brain activity in areas such as the insula, anterior cingulate cortex, and amygdala, indicating increased interoceptive awareness and cognitive load. Pre-attentive processing and sensory gating show exaggerated responses, while sustained attention and attentional control demand additional cognitive resources. These patterns reflect an interplay between heightened sensitivity to internal stimuli and cognitive processing challenges in IBS.

CONCLUSION

This review highlights specific attentional deficits and biases in IBS, suggesting they may contribute to symptom exacerbation and emotional distress. Further research is needed to explore the underlying mechanisms and potential therapeutic interventions.

The Relationship Between Irritable Bowel Syndrome and Metabolic Syndrome: A Systematic Review and Meta-Analysis of 49,662 Individuals

BACKGROUND

Studies have shown mixed results regarding the association between irritable bowel syndrome (IBS) and metabolic syndrome (MS); This study aimed to assess the susceptibility of IBS patients to MS and its individual components.

METHODS

PubMed, Scopus, Embase, and Web of Science were searched on 1/1/2023. Eligible studies were screened, and data on study characteristics, IBS diagnostic criteria, and metabolic syndrome components were extracted. Data were analysed in RevMan 5.4, with results reported as relative risk (RR) or mean difference (MD) and 95% confidence intervals. Statistical significance was set at p < 0.05.

RESULTS

IBS was associated with an increased risk of MS (RR = 2.05, 95% CI = 1.50-2.79, p < 0.00001), with a higher risk among IBS-D patients (RR = 3.09, 95% CI = 2.41-3.97, p < 0.00001). IBS patients showed increased HOMA-IR (MD = 0.21, 95% CI = 0.15-0.26, p < 0.00001), higher obesity risk (RR = 1.46, 95% CI = 1.10-1.93, p = 0.009), elevated BMI (MD = 1.51, 95% CI = 0.98-2.03, p-value < 0.00001), waist circumference (MD = 5.01, 95% CI = 1.29-8.72, p = 0.008), and an association with systolic hypertension (MD = -0.50, 95% CI = -0.60 to -0.40, p-value < 0.00001). IBS was also linked to higher LDL (MD = 5.98, 95% CI = 0.91-11.05, p = 0.02), total cholesterol (MD = 12.21, 95% CI = 6.23-18.18, p < 0.0001), and triglycerides (MD = 11.93, 95% CI = 11.55-12.31, p < 0.00001).

CONCLUSIONS

This analysis indicates a potential association between IBS and metabolic syndrome, including its components such as obesity, hypertension, and lipid profile abnormalities. However, significant heterogeneity among studies limits the generalisability of these findings. Clinicians should remain aware of the possible link and consider individualised preventive and management strategies.

Past Adversity Influencing Now (PAIN): perspectives on the impact of temporal language on the persistence of pain

Persistent pain is a significant healthcare issue, often unresponsive to traditional treatments. We argue for incorporating non-biomedical perspectives in understanding pain, promoting more comprehensive solutions. This article explores how language, specifically time-related terms, may affect the persistence (stickiness) of pain. We delve into how language influences one's experience of the world, especially in understanding pain through spatial metaphors. Notably, time perceptions differ across languages and cultures and there is no absolute construct of temporal pain experience. In English, time is viewed linearly as past, present, and future. We introduce a framework called Past Adversity Influencing Now (PAIN) which includes various temporal phases of pain; Past Perfect, Past Imperfect, Present, Future Imperfect, and Future Perfect. We suggest that past negative memories (emotional memory images) can "trap" individuals in a "sticky" pain state. We speculate that the process of diagnosing pain as "chronic" may solidify this "stickiness", drawing from the ancient Greek idea of "logos", where pain communicates a message across time and space needing recognition. Our PAIN framework encourages examining pain through a temporal lens, guiding individuals towards a more positive future.

A New Experimental Design to Examine Cognitive Biases for Gastrointestinal Related Stimuli in Children and Adolescents

Cognitive biases toward disorder-specific stimuli are suggested as crucial to the development and maintenance of symptoms in adults with functional gastrointestinal disorders (FGID). Functional abdominal pain disorders (FAPD), a subtype of FGID, are common in children and adolescents, but the influence of cognitive biases is sparsely examined. This study aimed to (1) develop a new experimental design for assessing cognitive biases toward gastrointestinal stimuli in children and adolescents (aged 8 to 17 years) and (2) derive comparative data on bias toward gastrointestinal stimuli using a healthy "normative" sample. The online experimental design-BY-GIS (Bias in Youth toward GastroIntestinal-related Stimuli)-includes a word task and a picture task. Stimuli in both tasks are related to general and gastrointestinal symptoms, and the design includes three phases: (1) encoding, (2) free recall, and (3) recognition. Data were collected between April 2022 and April 2023 from 96 healthy participants (Mage = 12.32, 47.92% female). Adolescents were significantly better at recalling words than children (p = 0.03), whereas there were no significant gender or age differences with regard to recalling pictures (p > 0.05). Across age and gender, participants performed above chance level in the recognition phases of both tasks. The results support that the design is suitable within the age span.

The neurobiology of irritable bowel syndrome

Irritable bowel syndrome (IBS) is the most prevalent disorder of brain-gut interactions that affects between 5 and 10% of the general population worldwide. The current symptom criteria restrict the diagnosis to recurrent abdominal pain associated with altered bowel habits, but the majority of patients also report non-painful abdominal discomfort, associated psychiatric conditions (anxiety and depression), as well as other visceral and somatic pain-related symptoms. For decades, IBS was considered an intestinal motility disorder, and more recently a gut disorder. However, based on an extensive body of reported information about central, peripheral mechanisms and genetic factors involved in the pathophysiology of IBS symptoms, a comprehensive disease model of brain-gut-microbiome interactions has emerged, which can explain altered bowel habits, chronic abdominal pain, and psychiatric comorbidities. In this review, we will first describe novel insights into several key components of brain-gut microbiome interactions, starting with reported alterations in the gut connectome and enteric nervous system, and a list of distinct functional and structural brain signatures, and comparing them to the proposed brain alterations in anxiety disorders. We will then point out the emerging correlations between the brain networks with the genomic, gastrointestinal, immune, and gut microbiome-related parameters. We will incorporate this new information into a systems-based disease model of IBS. Finally, we will discuss the implications of such a model for the improved understanding of the disorder and the development of more effective treatment approaches in the future.

Psychopathological and neuropsychological disorders associated with chronic primary visceral pain: Systematic review

The World Health Organization (WHO), in its last review of its International Classification of Diseases, established a new classification for chronic pain. Among the principal categories, of particular interest is chronic primary pain as a new type of diagnosis in those cases in which the etiology of the disease is not clear, being termed as chronic primary visceral pain when it is situated in the thorax, abdomen, or pelvis. Due to the novelty of the term, the objective of the systematic review was to examine the psychopathological and neuropsychological disorders associated with chronic primary visceral pain. We carried out a search of the scientific literature following the PRISMA directives using the Pubmed, Medline, PsycInfo and Scopus databases. A total of 33 articles were selected after applying the inclusion and exclusion criteria. The analysis of the studies showed that most persons with chronic primary visceral pain suffer from at least one psychological disorder; the most prevalent being anxiety, depressive or somatoform disorders. The most frequent psychopathological symptoms are anxiety, depression and somatization. Similarly, the findings are insufficient to determine the existence of deficits in the domains of executive functioning, memory and intelligence. However, the existence of attention biases does seem to be clear. This review supposes a starting point for conceptualizing chronic primary visceral pain. It is necessary to continue further research so as to obtain a better understanding of this pathology and the disorders associated.

Emotional stress responsivity of patients with IBS - a systematic review

OBJECTIVE

Irritable bowel syndrome (IBS) is a highly prevalent disorder of the gut-brain interaction characterized by abdominal discomfort and pain associated with altered bowel habits in the absence of structural abnormalities. Chronic psychological stress is considered a risk factor for the development of IBS. The multifactorial pathogenesis involves complex interactions between biological, psychological and social factors, yet the underlying mechanisms have not been fully understood.

METHODS

We systematically reviewed the literature from the databases MEDLINE, Embase and PsycINFO to assess stress responsivity of patients with IBS in comparison to healthy individuals, specifically focusing acute psychological stressors.

RESULTS

A total of 37 case-control studies were included in the narrative synthesis. Findings comprised subjective changes in emotion (k = 18) and of gastrointestinal symptoms (k = 8) as well as objective parameters of gastrointestinal motility (k = 10), autonomic nervous system (k = 23), hypothalamic-pituitary-adrenal axis (k = 11), functional brain activity (k = 7) and immune system (k = 3). Mental stress was found to increase IBS-specific symptomatology and alter gastrointestinal motility. Some patients with IBS showed stress-induced emotional hyperresponsivity and different patterns of neural activation. Autonomic and endocrine stress responses depend on the type of stressor and showed no clear evidence of differential reactivity, partly due to confounding factors. Data on acute immunological changes remains sparse and requires further investigation.

CONCLUSIONS

Current evidence suggests altered stress reactivity in patients with IBS however, it remains unclear whether it can be attributed to the syndrome itself or the high prevalence of psychiatric comorbidities.

Short term relief of multisite chronicpain with Bowen Therapy: A double-blind, randomized controlled trial

INTRODUCTION

Bowen Therapy, a form of soft tissue manipulation, is commonly used to treat musculoskeletal conditions; yet, there is little evidence for its efficacy. The goal of the study was to investigate the impact of Bowen Therapy on pain and function in people with chronic pain in multiple locations. Additionally, we examined the mechanisms of effect through monitoring the nociceptive and autonomic nervous systems.

METHOD

The study was a double-blind, randomized controlled trial involving 31 people with chronic pain. Participants were randomized into real and sham therapy groups. Each group received 6 sessions of therapy over 8 weeks. The primary outcome measures of pain and function were assessed using standard questionnaires. Quantitative sensory testing was used to assess the nociceptive system, while recordings of heart rate variability and skin conductance were used to assess the autonomic nervous system. Outcome measures were assessed at baseline and at 1- and 6-weeks following completion of the intervention.

RESULTS

The real therapy group had a significantly lower pain score 1-week following the intervention compared to the sham group. There were no differences between groups at the final follow-up or in the function measures. There was no significant change in the nociceptive measures but there was evidence of increased activation of the sympathetic nervous system.

DISCUSSION

Bowen Therapy gave rise to a short-term reduction in pain that was not evident in a sham therapy group. The mechanisms of action of Bowen Therapy remain uncertain but may involve sympathoexcitation.

Sex Differences Linking Pain-Related Fear and Interoceptive Hypervigilance: Attentional Biases to Conditioned Threat and Safety Signals in a Visceral Pain Model

Although the broad role of fear and hypervigilance in conditions of the gut-brain axis like irritable bowel syndrome is supported by converging evidence, the underlying mechanisms remain incompletely understood. Even in healthy individuals, it remains unclear how pain-related fear may contribute to pain-related attentional biases for acute visceral pain. Building on our classical fear conditioning work in a clinically relevant model of visceral pain, we herein elucidated pain-related attentional biases shaped by associative learning in healthy women and men, aiming to elucidate possible sex differences and the role of psychological traits. To this end, we compared the impact of differentially conditioned pain-predictive cues on attentional biases in healthy women and men. Sixty-four volunteers accomplished a visual dot-probe task and subsequently underwent pain-related fear conditioning where one visual cue (CS⁺) was contingently paired with a painful rectal distention (US) while another cue remained unpaired (CS^-). During the following test phase, the dot-probe task was repeated to investigate changes in attentional biases in response to differentially valenced cues. While pain-related learning was comparable between groups, men revealed more pronounced attentional engagement with the CS⁺ and CS^- whereas women demonstrated stronger difficulties to disengage from the CS⁺ when presented with a neutral cue. However, when both CS⁺ and CS^- were presented together, women revealed stronger difficulties to disengage from the CS^-. Regression analyses revealed an interaction of sex, with negative affect predicting stronger avoidance of the CS⁺ and stronger difficulties to disengage attention from the CS^- in men. These results provide first evidence that pain-related fear conditioning may induce attentional biases differentially in healthy women and men. Hence, sex differences may play a role in attentional mechanisms underlying hypervigilance, and may be modulated by psychological vulnerability factors relevant to chronic visceral pain.

Treating irritable bowel syndrome through an interdisciplinary approach

Irritable bowel syndrome (IBS) is a functional disorder with a multifactorial etiology and a complex clinical picture. The recent discovery of the dysregulation of the gut-brain axis as an important pathogenetic mechanism for the development of IBS is a kind of breakthrough in the understanding of IBS and prevalent comorbidities. Nevertheless, IBS treatment still causes many problems and often turns out to be ineffective or brings only short-term effects in reducing symptom severity. In reference to the characteristics of IBS, including new findings regarding etiopathogenesis, an interdisciplinary treatment approach is proposed and the roles of medical and psychological interventions are underlined. The literature search was conducted using electronic databases with a focus on the latest publications. The review may be useful for matching the best strategy of IBS management.

Role of brain imaging in disorders of brain-gut interaction: a Rome Working Team Report

Imaging of the living human brain is a powerful tool to probe the interactions between brain, gut and microbiome in health and in disorders of brain-gut interactions, in particular IBS. While altered signals from the viscera contribute to clinical symptoms, the brain integrates these interoceptive signals with emotional, cognitive and memory related inputs in a non-linear fashion to produce symptoms. Tremendous progress has occurred in the development of new imaging techniques that look at structural, functional and metabolic properties of brain regions and networks. Standardisation in image acquisition and advances in computational approaches has made it possible to study large data sets of imaging studies, identify network properties and integrate them with non-imaging data. These approaches are beginning to generate brain signatures in IBS that share some features with those obtained in other often overlapping chronic pain disorders such as urological pelvic pain syndromes and vulvodynia, suggesting shared mechanisms. Despite this progress, the identification of preclinical vulnerability factors and outcome predictors has been slow. To overcome current obstacles, the creation of consortia and the generation of standardised multisite repositories for brain imaging and metadata from multisite studies are required.

All's Bad That Ends Bad: There Is a Peak-End Memory Bias in Anxiety

The peak-end memory bias has been well documented for the retrospective evaluation of pain. It describes that the retrospective evaluation of pain is largely based on the discomfort experienced at the most intense point (peak) and at the end of the episode. This is notable because it means that longer episodes with a better ending can be remembered as less aversive than shorter ones; this is even if the former had the same peak in painfulness and an overall longer duration of pain. Until now, this bias has not been studied in the domain of anxiety despite the high relevance of variable levels of anxiety in the treatment of anxiety disorders. Therefore, we set out to replicate the original studies but with an induction of variable levels of anxiety. Of 64 women, half watched a clip from a horror movie which ended at the most frightening moment. The other half watched an extended version of this clip with a moderately frightening ending. Afterward, all participants were asked to rate the global anxiety which was elicited by the video. When the film ended at the most frightening moment, participants retrospectively reported more anxiety than participants who watched the extended version. This is the first study to document that the peak-end bias can be found in the domain of anxiety. These findings require replication and extension to a treatment context to evaluate its implications for exposure therapy.

Validity of Commonly Used Heart Rate Variability Markers of Autonomic Nervous System Function

BACKGROUND

Despite strong reservations regarding the validity of a number of heart rate variability (HRV) measures, these are still being used in recent studies.

AIMS

We aimed to compare the reactivity of ostensible sympathetic HRV markers (low and very low frequency [LF and VLF]) to that of electrodermal activity (EDA), an exclusively sympathetic marker, in response to cognitive and orthostatic stress, investigate the possibility of LF as a vagal-mediated marker of baroreflex modulation, and compare the ability of HRV markers of parasympathetic function (root mean square of successive differences [RMSSD] and high frequency [HF]) to quantify vagal reactivity to cognitive and orthostatic stress.

RESULTS

None of the purported sympathetic HRV markers displayed a reactivity that correlated with electrodermal reactivity. LF (ms2) reactivity correlated with the reactivity of both RMSSD and HF during baroreflex modulation. RMSSD and HF indexed the reactivity of the parasympathetic nervous system under conditions of normal breathing; however, RMSSD performed better as a marker of vagal activity when the task required breathing changes.

CONCLUSIONS

Neither LF (in ms2 or normalized units [nu]) nor VLF represent cardiac sympathetic modulation of the heart. LF (ms2) may reflect vagally mediated baroreflex cardiac effects. HRV linear analysis therefore appears to be restricted to the determination of vagal influences on heart rate. With regard to HRV parasympathetic markers, this study supports the suggestion that HRV frequency domain analyses, such as HF, should not be used as an index of vagal activity in study tasks where verbal responses are required, as these responses may induce respiratory changes great enough to distort HF power.

Automatic processes and self-regulation of illness

Research on the Commonsense Self-Regulation Model has emphasised reflective/conscious perceptual processes regarding illness threat (beliefs about symptoms, consequences, timeline, and curability) in predicting and changing coping behaviours. Understanding of illness self-regulation and avenues for intervention might be enriched by consideration of automatic processes that influence the recognition and identification of illness, response to illness, and ongoing management. This article adopts an integrative approach to (1) outline the theoretical importance of implicit processes in patients' self-regulation of illness and methods to study them; (2) review research evidence for these processes, including interventions tested to modify them; and (3) outline avenues for future research. A substantial body of research on implicit processes (cognitive bias and interpretational bias) in illness maintenance in chronic illness has recently been extended to detection and interpretation of acute illness and new perspectives relating to the self-system. There is encouraging evidence that cognitive accessibility of coping and implicit attitudes may impact upon coping behaviours. Procedures that strategically automatise coping responses and create habits have considerable promise. We outline an agenda for future research in which health psychology accepts the challenge posed by the interplay of the reflective and associative systems in promoting effective self-regulation of illness.

Altered attentional control linked to catastrophizing in patients with irritable bowel syndrome

OBJECTIVES

Our study aimed to investigate differences in attentional control between patients with irritable bowel syndrome (IBS) and healthy participants and to examine the link between attentional control and IBS catastrophizing. Previous research has shown that patients with chronic functional illnesses have lower levels of attentional control. However, no previous study has found altered attentional control in patients with IBS or directly investigated the link between attentional control and catastrophizing. We also aimed to establish whether anxiety is associated with attentional functions in patients with IBS.

DESIGN AND METHODS

In this cross-sectional study, we compared 41 IBS patients with 39 healthy-matched control participants on attentional functions using an attention network task. IBS catastrophizing (Gastrointestinal Cognitions), IBS symptom severity (GSRS-IBS), Depression, Anxiety, and Stress (DASS-21), and Visceral Anxiety Sensitivity were assessed using self-report measures.

RESULTS

Patients with IBS had lower attentional control compared to healthy participants, t (78) = -2.75, p = .007, d = .62. Groups did not differ in alerting or orienting attention. IBS patients with lower attentional control scored higher on IBS catastrophizing than those with higher attention control, t (38.59) = 2.19, p = .032, d = .66. Anxiety was related to orienting attention in the IBS group (ρ = .38, p = .015).

CONCLUSIONS

Patients with IBS displayed reduced attentional control. Crucially, those patients with lower attentional control also had more catastrophizing thoughts than patients with better attentional control. These findings suggest that improving attentional control could be a valid target for psychological interventions for IBS. Statement of contribution What is already known on this subject? It has been hypothesised that psychological processes play a role in the maintenance of irritable bowel syndrome (IBS), and altered levels of attentional control have been found in patients with other functional illnesses but not yet in patients with IBS. Pain catastrophizing, a maladaptive thinking pattern, has been linked with IBS symptom severity, and previous research has shown an association between attentional control and intrusive thoughts. Whether there is an association between catastrophizing thoughts and attentional control in patients with IBS is unknown. What does this study add? Patients with irritable bowel syndrome show reduced levels of attentional control. IBS patients with lower levels of attentional control have more catastrophizing thoughts. Therapies emphasizing attentional control training may help reduce catastrophizing.

Towards a systems view of IBS

Despite an extensive body of reported information about peripheral and central mechanisms involved in the pathophysiology of IBS symptoms, no comprehensive disease model has emerged that would guide the development of novel, effective therapies. In this Review, we will first describe novel insights into some key components of brain-gut interactions, starting with the emerging findings of distinct functional and structural brain signatures of IBS. We will then point out emerging correlations between these brain networks and genomic, gastrointestinal, immune and gut-microbiome-related parameters. We will incorporate this new information, as well as the reported extensive literature on various peripheral mechanisms, into a systems-based disease model of IBS, and discuss the implications of such a model for improved understanding of the disorder, and for the development of more-effective treatment approaches in the future.

Increased attentional network functioning related to symptom severity measures in females with irritable bowel syndrome

BACKGROUND

Increased attention to gastrointestinal (GI) symptoms and disease-specific contexts may play an important role in the enhanced perception of visceral stimuli frequently reported in patients with irritable bowel syndrome (IBS). In this study, we test the hypothesis that altered attentional mechanisms underlie central pain amplification in IBS.

METHODS

To evaluate brain networks that support alerting, orienting, and executive attention, we employed the attention network test (ANT), a modified flanker task which measures the efficiency of functioning of core attentional networks, during functional magnetic resonance imaging in 15 IBS patients (mean age = 31 [11.96]) and 14 healthy controls (HCs; mean age = 31 [10.91]).

KEY RESULTS

Patients with IBS, compared to HCs, showed shorter reaction times during the alerting and orienting conditions which were associated with greater activation of anterior midcingulate and insular cortices, and decreased activity in the right inferior frontal junction and supplementary motor cortex. Patients also showed activation in the dorsal medial prefrontal cortex and concurrent thalamic deactivation during the executive control portion of the ANT relative to HCs, but no group difference in reaction times were found. The activity in brain regions showing group differences during the ANT were associated with measures of GI-specific anxiety, pain catastrophizing, and fear of uncertainty. In IBS, activity in the anterior midcingulate during alerting correlated with duration of GI-symptoms and overall symptom severity.

CONCLUSIONS & INFERENCES

Together, these results suggest that IBS patients have specific abnormalities in attentional network functioning and these deficits may underlie symptom-related anxiety, hypervigilance, and visceral hypersensitivity.