Effect of hypnotherapy and educational intervention on brain response to visceral stimulus in the irritable bowel syndrome
Background Gut-directed hypnotherapy can reduce IBS symptoms, but the mechanisms underlying this therapeutic effect remain unknown. Aim To determine the effect of hypnotherapy and educational intervention on brain responses to cued rectal distensions in IBS patients. Methods Forty-four women with moderate-to-severe IBS and 20 healthy controls (HCs) were included. Blood oxygen level dependent (BOLD) signals were measured by functional Magnetic Resonance Imaging (fMRI) during expectation and delivery of high- (45mmHg) and low-intensity (15mmHg) rectal distensions. Twenty-five patients were assigned to hypnotherapy (HYP) and 16 to educational intervention (EDU). Thirty-one patients completed treatments and posttreatment fMRI. Results Similar symptom reduction was achieved in both groups. Clinically successful treatment (all responders) was associated with significant BOLD attenuation during high-intensity distension in the dorsal and ventral anterior insula (cluster size 142, P=0.006, and cluster size 101, P=0.005 respectively). Moreover HYP responders demonstrated a prepost treatment BOLD attenuation in posterior insula (cluster sizes 59, P=0.05) while EDU responders had a BOLD attenuation in prefrontal cortex (cluster size 60, P=0.05). Prepost differences for expectation conditions were almost exclusively seen in the HYP group. Following treatment, the brain response to distension was similar to that observed in HCs, suggesting that the treatment had a normalising effect on the central processing abnormality of visceral signals in IBS. Conclusions The abnormal processing and enhanced perception of visceral stimuli in IBS can be normalised by psychological interventions. Symptom improvement in the treatment groups may be mediated by different brain mechanisms. Clinical trial number: NCT01815164.
Irritable bowel syndrome (IBS) is a common gastrointestinal disorder characterized by abdominal pain and altered bowel habits. The societal costs of the disorder are significant, as are its negative effects on quality of life. Medical treatment options are limited, but psychological treatments such as hypnotherapy have proven to be effective. Important pathophysiological mechanisms include disturbances in brain processing of visceral sensation and expectation of visceral sensation. Increased sensation of stimuli (hypersensitivity) is present in a subset of IBS patients to distensions in the lower part of the gastrointestinal tract, indicating a probable important pathophysiological mechanism in IBS. The overall aim of the thesis was to further study the central pathophysiological mechanisms involved in IBS. Specifically, we aimed to identify differences in brain response to standardized repeated rectal distensions and expectation of these stimuli between IBS patients (with or without perceptual rectal hypersensitivity), and healthy controls. Furthermore, we aimed to investigate IBS patients´ brain responses to standardized rectal distensions and expectation of these stimuli after either a successful course hypnotherapy or educational intervention.
Functional magnetic resonance imaging (fMRI) data were acquired and analyzed from 15 IBS patients with visceral hypersensitivity, and 18 IBS patients with normal visceral sensitivity (papers I and II). In paper III, fMRI data were analyzed from IBS patients who reported significant symptom reduction after either a course of hypnotherapy, or an educational intervention. FMRI data from IBS patients and healthy controls were also compared.
The findings reported in papers I and II suggest, that the differences in brain response between IBS patients with and without rectal hypersensitivity, can be explained by changes in brain response during the course of the experiment. Even though the brain responses were similar between groups during the early phase of the experiment, they became substantially different during the late phase. The IBS patients with rectal hypersensitivity demonstrated increased brain response in several brain regions and networks involved in visceral sensation and processing. In contrast, IBS patients with normal rectal sensitivity exhibited reduced brain response during the late phase of the experiment. As reported in paper III, similar symptom reduction was achieved for both treatments. The symptomatic improvement was associated with a reduction of response in the anterior insula, indicating an attenuated awareness of the stimuli. The hypnotherapy group had a reduction of response in the posterior insula, indicating less input to the brain, possibly due to changed activity in endogenous pain modulatory systems. In patients who reported significant symptom reduction following treatment, the brain response to rectal distension got more similar to that observed in healthy controls.
The results from papers I and II indicate that a subpopulation of IBS patients lacks the ability to habituate to repeated rectal distensions and expectation of these stimuli. Results from paper III indicate that the abnormal processing of visceral stimuli in IBS can be altered, and that the treatments probably had a normalizing effect on the central processing abnormality of visceral signals in IBS.
Linköping University, Department of Clinical and Experimental Medicine, Division of Neuro and Inflammation Science. Linköping University, Faculty of Medicine and Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Heart and Medicine Center, Department of Gastroentorology.
Schaubcylindrichnus is an important trace fossil used in the characterization of offshore and shoreface depositional environments. Our understanding of this trace has followed a winding path including the introduction of several new ichnospecies and the subsequent recent synonymization into one ichnospecies. Likewise, our understanding of the ethological interpretation of the trace fossil has evolved from gregarious head-down deposit feeders to filter feeders, until it recently was shown that the tracemaker probably was a funnel feeder. Although several ichnospecies were recently synonymized into one ichnospecies, Schaubcylindrichnus coronus, variability in the number of tubes per sheaf and abundance of nested tubes, i.e., tubes that break up older tubes, were observed between different settings. These differences were studied in close detail at Miocene outcrops in Japan and Taiwan where the trace fossil occurs copiously and therefore allows the intraspecific morphological variability to be addressed. Around 2000 specimens from Japan and Taiwan were studied. The results show a distinct tendency for higher tube numbers in the offshore facies where sediments are characterized by higher silt/mud content, suggesting that S. coronus with higher tube numbers were constructed in a calm environment allowing longer dwelling periods. The increased abundance of nested tubes in settings characterized by thin sand layers indicate that the nested tubes are a reparation response to erosional events destroying the feeding funnels at the sediment-water interface. Consequently, tube number per sheaf and abundance of nested tubes may be used to further characterize the depositional environment in shoreface to offshore facies.