Psychological Co-morbidity in Functional Gastrointestinal Disorders: Epidemiology, Mechanisms and Management.

Functional gastrointestinal disorder (FGID) is one of the commonest digestive diseases worldwide and leads to significant morbidity and burden on healthcare resource. The putative bio-psycho-social pathophysiological model for FGID underscores the importance of psychological distress in the pathogenesis of FGID. Concomitant psychological disorders, notably anxiety and depressive disorders, are strongly associated with FGID and these psychological co-morbidities correlate with severity of FGID symptoms. Early life adversity such as sexual and physical abuse is more commonly reported in patients with FGID. There is mounting evidence showing that psychological disorders are commonly associated with abnormal central processing of visceral noxious stimuli. The possible causal link between psychological disorders and FGID involves functional abnormalities in various components of the brain-gut axis, which include hypothalamic-pituitary-adrenal system, sympathetic and parasympathetic nervous system, serotonergic and endocannabinoid systems. Moreover, recent studies have also shown that psychological distress may alter the systemic and gut immunity, which is increasingly recognized as a pathophysiologic feature of FGID. Psychotropic agent, in particular antidepressant, and psychological intervention such as cognitive behavioral therapy and meditation have been reported to be effective for alleviation of gastrointestinal symptoms and quality of life in FGID patients. Further studies are needed to evaluate the impact of early detection and management of co-morbid psychological disorders on the long-term clinical outcome and disease course of FGID.