Novel techniques to study visceral hypersensitivity in irritable bowel syndrome. Curr Gastroenterol Rep. 2008;10:369-378. [PMID: 18627648 DOI: 10.1007/s11894-008-0071-2]

Measurement of Pain and Related Symptoms in Irritable Bowel Syndrome: The Use of Validated Pain Measurement Tools

This paper reviews the tools available to assess outcomes of treatment in irritable bowel syndrome, especially the effect on abdominal pain. Tools were identified through a wide-ranging scrutiny of PubMed and Google Scholar, together with a review of further references quoted in those publications. It critically considers their development, relevance and reliability. The Irritable Bowel Severity Scoring System (IBS-SSS) was the first simple method of monitoring the progress of the disease and its treatment. It led on to other instruments, such as The Irritable Bowel Syndrome Quality of Life (IBS-QOL). It is easier to read and faster to complete than the IBS-SSS., However, these and other tools were developed for English speaking populations. This review considers the impact of ethnicity and gender, together with the lack of information on the effect of age on the potential validity of these tools in other populations. Issues with the adequacy and appropriateness of translations of such tools are discussed. The overall conclusion is that there are few tools which meet the criteria necessary to place confidence in their validity as appropriate measures of patient outcomes.

Focus on the use of antidepressants to treat pediatric functional abdominal pain: current perspectives

Chronic abdominal pain is frequently encountered in pediatric practice. A large proportion of cases meet Rome criteria for abdominal pain-functional gastrointestinal disorders (AP-FGIDs). These disorders are costly and, in some cases, lead to impairment of daily functioning and overall quality of life. Pathophysiologic mechanisms include early stressful events, visceral hypersensitivity, dysmotility, changes in intestinal microbiota, and altered central nervous system processing. They are considered disorders of the brain-gut interaction. The diagnosis is made on clinical grounds using symptom-based criteria (Rome criteria). Anxiety and depressive symptoms are more prevalent in patients with AP-FGIDs. Therefore, attention has been directed to the use of neuromodulators as potential interventions for AP-FGIDs. Antidepressants are one type of neuromodulators, and one of the most studied drugs for the management of AP-FGIDs in adult and pediatric population. Data available in pediatric population have significant limitations including nonuniform methodology with different study designs and primary endpoints. Evidence of the efficacy of antidepressants in the management of pediatric AP-FGIDs is not consistent. There is an urgent need for well-designed randomized clinical trials using age-appropriate validated outcome measures. Careful consideration must be given to adverse effects, particularly increased suicidal ideation.

Sex differences in emotion-related cognitive processes in irritable bowel syndrome and healthy control subjects

Greater responsiveness of emotional arousal circuits in relation to delivered visceral pain has been implicated as underlying central pain amplification in irritable bowel syndrome (IBS), with female subjects showing greater responses than male subjects. Functional magnetic resonance imaging was used to measure neural responses to an emotion recognition paradigm, using faces expressing negative emotions (fear and anger). Sex and disease differences in the connectivity of affective and modulatory cortical circuits were studied in 47 IBS (27 premenopausal female subjects) and 67 healthy control subjects (HCs; 38 premenopausal female subjects). Male subjects (IBS+HC) showed greater overall brain responses to stimuli than female subjects in prefrontal cortex, insula, and amygdala. Effective connectivity analyses identified major sex- and disease-related differences in the functioning of brain networks related to prefrontal regions, cingulate, insula, and amygdala. Male subjects had stronger connectivity between anterior cingulate subregions, amygdala, and insula, whereas female subjects had stronger connectivity to and from the prefrontal modulatory regions (medial/dorsolateral cortex). Male IBS subjects demonstrate greater engagement of cortical and affect-related brain circuitry compared to male control subjects and female subjects, when viewing faces depicting emotions previously shown to elicit greater behavioral and brain responses in male subjects.

A meta-analysis of the therapeutic effects of amitriptyline for treating irritable bowel syndrome

OBJECTIVE

We aimed to evaluate the efficacy of amitriptyline as a therapeutic option for irritable bowel syndrome (IBS) through a meta-analysis of randomized controlled trials.

METHODS

For the years from 1966 until May 2012, PubMed, Scopus, Web of Science and the Cochrane Central Register of Controlled Trials were searched for double-blind, placebo-controlled trials investigating the efficacy of amitriptyline in the management of IBS.

RESULTS

Four randomized, placebo-controlled clinical trials met our criteria and were included in the meta-analysis. The pooled relative risk for clinical improvement with amitriptyline therapy was 4.18 (95% CI: 2.00 to 8.77, p=0.0001).

CONCLUSION

It was thus concluded that amitriptyline exhibits a clinically and statistically significant control of IBS symptoms.

Evidence for alterations in central noradrenergic signaling in irritable bowel syndrome

BACKGROUND/AIMS

Alterations in noradrenergic (NE) signaling have been implicated in the pathophysiology of irritable bowel syndrome (IBS), and adrenergic receptors are potential treatment targets.

METHODS

To characterize central NE signaling in IBS, 11 patients and 11 healthy controls (HCs) were studied 3 times during an auditory oddball vigilance task after double-blind ingestion of the α2-adrenoreceptor (α2AR) antagonist yohimbine (YOH), the α2AR agonist clonidine (CLO), or placebo (PLA). Regional cerebral glucose metabolism was measured with [¹⁸F] fluorodeoxyglucose (FDG) positron emission tomography (PET). Measures of anxiety, early-life trauma, plasma NE and blood pressure were acquired.

RESULTS

Patients had higher plasma NE levels than HCs before and after ingestion of all drugs (all p<0.05). YOH increased plasma NE and more anxiety in patients than in HCs. After YOH, NE levels directly correlated with drug-induced increases in anxiety in IBS patients (r=0.61), but not in HCs. IBS patients showed less YOH-mediated reduction of activity in a central arousal circuit, consistent with fewer functional presynaptic α2AR. In HCs, but not in patients, activation of amygdala and subgenual anterior cingulate cortex (sgACC) was inversely correlated with activation of anterior mid cingulate cortex (aMCC), and state anxiety covaried directly with activity in limbic and right frontotemporal cortices, but indirectly with activity in the left frontotemporal cortex. YOH-mediated reduction of activity in brainstem and amygdala inversely correlated with early life trauma.

CONCLUSIONS

IBS patients showed evidence for increased noradrenergic activity consistent with downregulation of presynaptic inhibitory α2ARs. Activity within central arousal circuits was biased toward greater excitability and reduced corticolimbic inhibition in IBS. Early life trauma may be one mediator of these abnormalities.

Advances in understanding the relationship between functional dyspepsia and mental factors

The co-morbidity of functional dyspepsia (FD) and mental disorders is 42%-61%. Growing evidence shows that visceral hypersensitivity and abnormality of brain gut peptides are possibly responsible for the interactions between FD and mental disorders, and the brain-intestine axis plays a crucial role in the development of visceral pain. Functional magnetic resonance imaging is a novel and effective tool for studying visceral hypersensitivity. Gastric pain activates a wide range of cortical and subcortical structures, including the cortex of frontal lobe, anterior cingulate cortices, insula, thalamus and amygdala. Several studies show that selected serotonergic antidepressants and some traditional Chinese medicine can improve the symptoms, especially pain, of FD; however, the underlying mechanisms remain unclear.

Irritable bowel syndrome and the elusive mast cells

Irritable bowel syndrome (IBS) is the most common condition seen by gastroenterologists. It presents with alternating symptoms of bowel dysfunction that often worsens with stress. The cause of these symptoms eludes investigators and many attempts have been made to discover an underlying pathology. This is a daunting task since symptoms come and go, and change characteristics. Furthermore, the pathology of IBS is unlikely to be identical in all patients. In addition, all symptoms and all features studied thus far have a strong overlap with healthy volunteers. Elsewhere in this issue, Braak et al. report a well-designed clinical investigation in patients with IBS and come to the conclusion that IBS is not characterized by mast cell or other immune cell proliferation, but by immune dysregulation in the colon. Is this the final answer?

Do fluctuations in ovarian hormones affect gastrointestinal symptoms in women with irritable bowel syndrome?

BACKGROUND

An increase in gastrointestinal (GI) symptoms, including bowel discomfort, abdominal pain/discomfort, bloating, and alterations in bowel patterns, has been reported during premenses and menses menstrual cycle phases and the perimenopause period in women with and without irritable bowel syndrome (IBS).

OBJECTIVE

This article reviews the literature related to one possible physiological mechanism-declining or low ovarian hormone levels--that may underlie the occurrence or exacerbations of abdominal pain/discomfort at times of low ovarian hormones (menses, menopause) in women with or without IBS.

METHODS

To identify English-only review and data-based articles, PubMed was searched between January 1980 and September 2008 using the following terms: irritable bowel syndrome, functional gastrointestinal disorders, gastrointestinal motility, immune, pain, hyperalgesia, menstrual cycle, menopause, pregnancy, estrogen, estradiol (E(2)), and progesterone. Studies in animals and in humans were included; drug trials were excluded.

RESULTS

From our review of the literature, 18 papers were identified that were related either to the mechanisms accounting for menstrual cycle fluctuations (n = 12) or to the impact of menopausal status on symptoms of IBS (n = 6). One study reported that visceral pain sensitivity was significantly higher during menses than at other menstrual cycle phases in women with IBS (P < 0.05). Other menstrual cycle phase-linked symptoms, dysmenorrheal symptoms (cramping pain) in particular, were more intense in women with IBS. Animal studies have shed some light on the relationship of ovarian hormones to GI sensorimotor function.

CONCLUSION

The increase in GI symptoms around the time of menses and early menopause occurs at times of declining or low ovarian hormones, suggesting that estrogen and progesterone withdrawal may contribute either directly or indirectly. This review highlights the need for confirmatory preclinical and clinical studies to unravel the role of ovarian hormones in women with IBS.

Psychological adjustment and autonomic disturbances in inflammatory bowel diseases and irritable bowel syndrome

Psychological factors and the autonomic nervous system (ANS) are implicated in the pathogenesis of inflammatory bowel diseases (IBD) and irritable bowel syndrome (IBS). This study aimed to assess, firstly the way IBS and IBD patients cope with their pathology according to their affective adjustment and secondly the possible links between these affective adjustments and ANS reactivity. Patients with Crohn's disease (CD; n=26), ulcerative colitis (UC; n=22), or IBS (n=27) were recruited and compared to 21 healthy subjects based on psychological variables (trait- and state anxiety, depressive symptomatology, negative mood, perceived stress, coping, health locus of control) and sympatho-vagal balance through heart-rate variability monitored at rest. A principal component analysis, performed on all affective variables, isolated a leading factor labelled as "affective adjustment". In each disease, patients were distributed into positive and negative affective adjustment. In all the diseases, a positive affect was associated with problem-focused coping, and a negative affect with emotion-focused coping and external health locus of control. Results show that the sympatho-vagal balance varied according to the disease. In CD presenting positive affectivity, an adapted high sympathetic activity was observed. In UC, a parasympathetic blunt was observed in the presence of negative affectivity and an equilibrated sympatho-vagal balance in the presence of positive affectivity. In contrast, in IBS, an important dysautonomia (with high sympathetic and low parasympathetic tone) was constantly observed whatever the affective adjustment. In conclusion, this study suggests that the equilibrium of the ANS is differentially adapted according to the disease. This equilibrium is conjugated with positive affective and cognitive adjustment in IBD (CD and UC) but not in IBS.

Anger and childhood sexual abuse are independently associated with irritable bowel syndrome

OBJECTIVES

Irritable bowel syndrome (IBS) presents in the absence of identifiable organic pathology. Clinical and research literature has suggested that both childhood abuse and anger are linked to functional gastrointestinal conditions including IBS. The present study tested the predictions that IBS patients, when compared to patients with an organic bowel disease (Crohn's disease), have higher levels of trait and suppressed anger, and that these mediate the link between abuse and IBS.

DESIGN

The study was a cross-sectional multivariate comparison between groups of patients with IBS and Crohn's disease.

METHOD

Levels of self-reported trait and suppressed anger and recalled childhood abuse in patients with IBS (N=75) or Crohn's disease (N=76) were compared, using self-report questionnaires and controlling for other psychological characteristics (anxiety, depression, and dissociation).

RESULTS

Trait and suppressed anger were greater in IBS patients, and differences in trait anger remained significant after controlling for other psychological variables. Childhood sexual abuse was more prevalent in IBS than Crohn's disease patients but was unrelated to trait anger.

CONCLUSIONS

Higher levels of anger characterize IBS patients when compared to an organic bowel disease group, but do not explain the link between childhood abuse and IBS.

Efficacy of tricyclic antidepressants in irritable bowel syndrome: A meta-analysis

We aimed to evaluate the efficacy of tricyclic antidepressants (TCAs) as a therapeutic option for irritable bowel syndrome (IBS) through meta-analysis of randomized controlled trials. For the years 1966 until September 2008, PubMed, Scopus, Web of Science, and Cochrane Central Register of Controlled Trials were searched for double-blind, placebo-controlled trials investigating the efficacy of TCAs in the management of IBS. Seven randomized, placebo-controlled clinical trials met our criteria and were included in the meta-analysis. TCAs used in the treatment arm of these trials included amitriptyline, imipramine, desipramine, doxepin and trimipramine. The pooled relative risk for clinical improvement with TCA therapy was 1.93 (95% CI: 1.44 to 2.6, P < 0.0001). Effect size of TCAs versus placebo for mean change in abdominal pain score among the two studies was -44.15 (95% CI: -53.27 to -35.04, P < 0.0001). It is concluded that low dose TCAs exhibit clinically and statistically significant control of IBS symptoms.