Effects of personality traits on the manifestations of irritable bowel syndrome

Objective Previous studies have reported that patients with irritable bowel syndrome (IBS) show high neuroticism. However, the precise association between the IBS subtypes and the degree of neuroticism in younger populations is largely unknown. We tested our hypothesis that subjects with diarrhea-predominant IBS may have a higher degree of neuroticism than subjects without IBS or those with other subtypes of IBS. We also verified the additional hypothesis that the severity of neuroticism might be correlated with the severity of IBS in younger populations. Methods We conducted a cross-sectional survey of 557 university students, ranging in age from 18 to 21 years. Presence/ absence of IBS and determination of the IBS subtype was by the Rome II Modular Questionnaire, while the severity of IBS was determined by the IBS severity index (IBS-SI). The degree of neuroticism was evaluated using the Maudsely Personality Inventory (MPI). The presence/absence of psychological distress was measured with the K6 scale. Results Neuroticism scores in the subjects with diarrhea-predominant IBS were significantly higher than those in the non-IBS subjects or subjects with constipation-predominant IBS. The neuroticism scores were significantly correlated with the IBS-SI scores in all subjects with IBS. Conclusion These results suggest that neuroticism is involved in the pathophysiology of IBS in young subjects, especially in that of the diarrhea-predominant subtype.