The relationship of psychiatric disorder to gastrointestinal illness.

The definition of psychiatric illness by specific criteria has provided a new method for examining the relationship of certain gastrointestinal (GI) diseases to psychiatric disorder. Using this technique, researchers have found that rates of psychiatric diagnosis in patients with certain functional GI syndromes and Crohn's disease exceed those found in the general population and in comparably ill control groups. Timing of onset of both sets of symptoms (GI and psychiatric) suggests that the functional syndromes generally follow or coincide with the onset of psychiatric symptoms, whereas the onset of Crohn's disease is more independent. A relationship of psychiatric illness to other GI disease is suspected based on results of psychometric testing or on less structured attempts at psychiatric diagnosis employed in earlier studies. Psychiatric diagnosis by criteria definition may play an important role in more clearly understanding any relationship of psychiatric disorder to somatic GI disease as the applications of this scientific technique are expanded.