Autonomic nervous system dysregulation in irritable bowel syndrome

Background: Autonomic nervous system (ANS) regulation may be altered in functional diseases, including irritable bowel syndrome (IBS), but published data are not clear to date. The aim of the study was to analyze ANS function in IBS subjects classified by Rome III criteria and healthy controls using standardized technique. Methods: ANS activity was evaluated by autoregressive spectral analysis of RR interval and systolic arterial pressure variabilities, to obtain indices of sympatho-vagal modulation of the heart and of spontaneous cardiac baroreflex (α index). A symptom list was used to score 18 somatic complaints (score 0-180) (4SQ). Fatigue and stress were assessed through the use of a global scoring index (0-10). Key Results: We enrolled 41 IBS subjects (29 F, age 40 ± 2 years) and 42 healthy matched controls. Heart rate was higher in IBS than control subjects (69 ± 2 vs 61 ± 1; p < 0.001). The total variance of RR interval variability, and α index, were significantly lower in IBS compared to controls (1983.12 ± 384.64 ms2 vs 4184.55 ± 649.59 ms2; 18.1 ± 2 ms/mmHg vs 29 ± 3 ms/mmHg; p < 0.01). The α index results showed an inverse correlation with stress scores and somatic symptoms. Conclusions & Inferences: IBS subjects display a significant reduction in α index, an established marker of cardiac baroreflex. ANS dysfunction appears to be involved in the pathophysiology of IBS and its assessment may open new perspectives for clinical management of patients suffering from IBS. Autonomic nervous system (ANS) regulation is altered in patients with irritable bowel syndrome (IBS). The goal of the study was to assess ANS profile and its correlation with somatic perception in patients with IBS. We measured ANS function in 41 IBS patients and 42 healthy controls by means of a user-friendly and indirect non-invasive approach. IBS is associated with marked impairment of vagal regulation indices coupled to elevated subjective stress. Autonomic imbalance may have a role in the pathogenesis of IBS and its assessment may open new perspectives in clinical management of patients.