Increased Postprandial Colonic Motility and Autonomic Nervous System Activity in Patients With Irritable Bowel Syndrome: A Prospective Study

BACKGROUND/AIMS: The prevalence and severity of irritable bowel syndrome (IBS) declines with age, but the cause of this is unknown. This study tested 2 hypotheses: (1) autonomic nervous system responses to eating and bowel distention, measured by heart rate variability (HRV), differs by age in IBS patients and (2) HRV is correlated with colonic motility and IBS symptoms. METHODS: One hundred and fifty-six Rome III positive IBS patients and 31 healthy controls underwent colonic manometry with bag distention in the descending colon, followed by ingestion of an 810-kcal meal. HRV, evaluated by low frequency (%LF; 0.04–0.15 Hz) component, high frequency (%HF; 0.15–0.40 Hz) component, and the LF/HF ratio, was measured during colonic distention and after the meal. Motility index and subjective symptom scores were simultaneously quantified. RESULTS: Both colonic distention and eating decreased %HF and increased the LF/HF ratio, and both indices of autonomic nervous system correlated with age. In IBS patients, %HF negatively correlated with the postprandial motility index after adjusting for age. The %HF and LF/HF ratios also correlated with psychological symptoms but not bowel symptoms in IBS patients. CONCLUSION: Decreased vagal activity is associated with increase in age and greater postprandial colonic motility in patients with IBS, which may contribute to postprandial symptoms.

Biopsychosocial Model of Irritable Bowel Syndrome

Irritable bowel syndrome (IBS) is a common chronic disorder seen in gastroenterology and primary care practice. It is characterized by recurrent abdominal pain or discomfort associated with disturbed bowel function. It is a heterogeneous disorder with varying treatments, and in this regard physicians sometimes struggle with finding the optimal approach to management of patients with IBS. This disorder induces high health care costs and variably reduces health-related quality of life. IBS is in the class of functional gastrointestinal disorders, and results from dysregulation of central and enteric nervous system interactions. Psychosocial factors are closely related to their gut physiology, associated cognitions, symptom manifestations and illness behavior. Therefore, it is important for the physician to recognize the psychosocial issues of patients with IBS and in addition to build a good patient-physician relationship in order to optimize treatment. This review focuses on the interaction between psychological and physiological factors associated with IBS by using a biopsychosocial model. In this article, we describe (1) the predisposing psychological features seen in early life; (2) the psychological factors associated with life stress, the symptom presentation, and their associated coping patterns; (3) gut pathophysiology with emphasis on disturbances in motility, visceral hypersensitivity and brain-gut interactions; and finally (4) the clinical outcomes and effective treatments including psychotherapeutic methods.