Effect of acute stress on anorectal physiology in normal healthy volunteers

Visceral hypersensitivity occurs in many patients with irritable bowel syndrome; however, it is more common in those with high anxiety levels, raising the possibility that it is merely a reflection of underlying anxiety. The aim of this study was to assess the effect of acute stress on anorectal motility and sensitivity in normal healthy volunteers. Anorectal responses to balloon distension were assessed in 14 healthy volunteers (aged from 24–52 years; 11 women) on three separate occasions in random order during exposure to either cold pain, mental stress or control conditions. Both subjective and objective measures of stress increased significantly during both stress studies [subjective stress level (mean ± SEM): control 23 ± 2.9, cold pain 56 ± 5.4, mental stress 61 ± 6.5, P< 0.002; pulse rate: control 71 ± 0.5, cold pain 82 ± 0.9, mental stress 84 ± 1.2, P<0.01]. However, there were no changes in rectal sensitivity [volume to discomfort (ml): control 190 ± 14.5, cold pain 198 ± 16.9, mental stress 180 ± 14.9]; rectal compliance (ml/cmH₂O; control 6.4 ± 0.56, cold pain 7.3 ± 0.86, mental stress 6.3 ± 0.6), or distension-induced motility (control 1405 ± 376, cold pain 1389 ± 387, mental stress 1021 ± 289). Acute stress does not effect the anorectal response to balloon distension in normal volunteers. Further studies are required to assess whether patients with irritable bowel syndrome respond in a similar or different way to acute stressful stimuli.