Neurocognitive Characteristics of Individuals with Irritable Bowel Syndrome.

Irritable bowel syndrome (IBS) is a systems-based brain-gut axis disorder. Cognitive functions reflect central affective and attentional processes that are driven by genetic and epigenetic influences and effect complex brain-gut interactions. These interactions include stress-induced changes in hypothalamic-pituitary-adrenal axis and autonomic nervous system, remodelling of the immune system, and alterations in microbiota composition. This review summarises current neurocognitive findings on patients with IBS. 13 studies of neurocognition in IBS patients were identified from PubMed, Ovid MEDLINE, EMBASE, and PsycINFO. The methodology and relevant findings were systematically analysed. There are alterations in both hot and cold cognitions in IBS patients. Consistently, attentional bias towards negative emotionally valenced and gastrointestinal symptom-related stimuli is found in hot cognition tasks, with other cold cognition differences including frontal executive dysfunction and stress-related hippocampal-mediated cognitive alterations. The effect of psychiatric comorbidity on a disorder level, as well as illness chronicity, on cognitive alterations requires further examination. Attentional bias and executive dysfunction in IBS gave support to its neural network alterations accounting for visceral hypersensitivity. Further prospective neuropsychological studies should examine the effect of chronicity, current symptom severity, and psychiatric comorbidity on the cognition in different IBS subtypes.