Temporal Dynamics of Stress, Affect, and Abdominal Pain in IBS : Insights from a Clinical Sample

Irritable bowel syndrome (IBS) has a complex aetiology involving biological and psychological alterations. Among others, stress seems to be a relevant factor for IBS symptom onset and exacerbation. Affective changes can be related to symptom severity and stressful experiences and may be valuable for therapeutic purposes. The aim of this study was to examine temporal dynamics of affect, stress, and symptom severity (specifically abdominal pain) in a sample of IBS patients. Thirty-two outpatients kept a diary with a set of short questionnaires (Affect scale, Symptom severity scale, and Daily stress measure) once a day, in the evening, for 14 days. Abdominal pain was modeled as a function of between-person, concurrent and lagged within-person effect of stress and affect controlling for autoregressive pain effects. Positive and negative affect exhibited concurrent effects on abdominal pain while stress did not. Daily variation in positive affect was associated with a decrease in pain while the opposite was true for negative affect. Positive and negative affect models explained over 40% of the variation in daily abdominal pain. Even though the models had a good fit, the amount of variance explained by positive and negative affect alone was relatively small (~7%) with high interindividual heterogeneity. It seems that day-to-day stress variations do not have a direct impact on abdominal pain, while affective dynamics appear closely related to pain variations.