Review article: The rationale for antidepressant therapy in functional gastrointestinal disorders.

The rationale for antidepressants in the treatment of functional gastrointestinal disorders (FGDs) has been the subject of much interest. However, because of our incomplete understanding of FGDs, this rationale remains unclear. A key point is whether the high degree of psychiatric co-morbidity associated with FGDs (40-90%) represents a shared pathophysiology or the ascertainment bias of tertiary referral patients. Our aims were four-fold: (i) to review the current rationale for antidepressant therapy in FGDs; (ii) to review the studies comparing the characteristics of FGDs with both organic gastrointestinal disease and psychiatric disorders; (iii) to propose a model of FGDs which explains the high psychiatric co-morbidity; (iv) to compare the treatment regimes and effectiveness of antidepressants in FGDs and psychiatric illnesses. The review highlights two important observations. Firstly, the characteristics of FGDs are similar to those of affective disorders and dissimilar to those of organic disease. Secondly, although antidepressants benefit FGD sufferers, their benefits in psychiatric illnesses are greater. We conclude that, in view of the degree of similarity between FGDs and affective disorders, FGDs could be considered as affective disorders in their own right and, if the prescription of antidepressants conformed to their use in affective disorders, FGD morbidity would be reduced.