Su2111 A Prospective Assessment of Cognitive Performance in Irritable Bowel Syndrome Reveals Persistent Visuospatial Memory Deficits

Abstract

Background: Irritable bowel syndrome (IBS) is a stress-related functional gastrointestinal disorder of the brain-gut axis. The cognitive neurobiological model of IBS (Kennedy et al., 2012), proposes that some of the key pathophysiological features, including stress-related changes in hypothalamic pituitary adrenal (HPA)-axis functioning, and the immune-mediated degradation of tryptophan along the kynurenine pathway, may impact on patients' cognitive performance. We recently provided support for this model by showing that patients with IBS exhibit a visuospatial memory deficit associated with alterations in both HPA axis activity and the kynurenine:tryptophan ratio (Kennedy et al., 2012). However, whether visuospatial memory dysfunction is a stable feature of IBS is currently unknown. AIM: To assess longitudinally if patients with IBS consistently exhibit visuospatial memory dysfunction in comparison to disease controls [Crohns disease (CD)] and healthy controls (HC). Methods: At baseline (visit 1) and 6 months later (visit 2), a cohort of IBS patients (baseline n=39; 6M/33F; mean age: 28 yrs; IQ: 105.5; BMI: 23.7; 6 month follow-up: n= 33), matched CD patients (baseline n= 18;11M/7F; mean age: 32 yrs; IQ: 103.4; BMI: 25.2; 6 month follow-up: n=17), and matched HC (baseline n=40;11M/29F; mean age 28 yrs; IQ: 108.5; BMI: 23.5; 6 month follow-up: n=33), were assessed using a selection of cognitive tests from the Cambridge Neuropsychological Test Automated Battery (CANTAB) and Stroop test. Abdominal pain severity at time of testing was reported by IBS patients on a scale ranging from 0-100. Results: At both visits IBS patients exhibited impaired visuospatial memory performance compared to HC, evidenced by significantly more errors on the Paired Associates Learning (PAL;visuospatial memory) 6 pattern stage at visit 1 (3.82±.85 vs 1.55±.38, p 05). Abdominal pain scores in IBS patients did not correlate with any PAL measures at visit1 & 2 (All p> .05). No significant group differences were identified across visit 1 & 2 on the Intra-Extra Dimensional Set Shift (IED;executive functioning); total errors (p>05),or Spatial working memory (SWM);total errors (p> 05).Conclusion: Impaired visuospatial memory performance is a persistent and domain-specific feature of cognitive performance in IBS that is independent of symptom severity. Future research strategies in IBS should aim to address how altered cognition, a neglected aspect of this highly prevalent and debilitating disorder, impacts on patient performance. Moreover, these results may inform future treatment strategies in a disorder that currently lacks uniformly effective therapies.