Table 1.

Summary of stress -induced physiologic changes in IBS

Function	Findings in IBS vs. controls
GI motility	Suppressed antral and small bowel motor activity and enhanced colonic motor activity
Visceral perception	Decreased rectal non-painful and pain thresholds to distension and electrostimulation during psychological stress in IBS but not in controls Higher stress, anxiety and anger ratings higher in IBS vs. controls
Intestinal permeability and secretion	Increased small intestinal and colonic permeability demonstrated in IBS but not measured in response to stress Net water flux was significantly lower in healthy women with moderate stress compared to those with low stress. Chloride secretion was lower and albumin was higher in moderate stress vs. low stress but not statistically significant
Autonomic tone	Increases in blood pressure and heart rate and shift to lower cardiosympathetic/vagal balance after mental stress in IBS and controls but no group differences
HPA axis	Increased basal levels of cortisol in IBS vs. controls Two studies show increased HPA axis response and one shows blunted response to hormone stimulation in IBS vs. controls Most studies report lack of a response to a meal and/or mental stressor in IBS HPA axis response varies depending on the type of physical stressor