Presidential address: Gastrointestinal illness and the biopsychosocial model

Objective: To review the evidence supporting the biopsychosocial model in understanding patients with gastrointestinal disorders (GI). Method: Essay of personal experience and review of related literature through a MEDLINE search. Results: Through clinical examples of three common gastrointestinal disorders, a case is made to refocus our understanding from a biomedical or disease-based model of illness to a biopsychosocial model. With the latter model, the psychosocial and biological predeterminants are seen to interact in the clinical expression of illness and disease. With gastroesophageal reflux disease, the evidence shows that stress can lead to amplification of heartburn symptoms that is independent of the degree of reflux. Functional gastrointestinal pain is "an illness without disease," where structural or physiological disturbance of the GI system does not exist. Rather, the symptoms are understood in terms of visceral hypersensitivity as modulated by central nervous system activity. With the Crohn's disease example, the clinical expression of the disorder is not explained by the degree of disease activity. Rather, the symptoms and impaired quality of life relate to preexisting psychosocial determinants. The observed association of stress with disease activation in Crohn's disease is explained by stress-related alterations in psychoimmunological function via the hypothalamic-pituitary-adrenal axis. Conclusions: Gastrointestinal disorders, as a model for other medical conditions, exemplify the important role of an integrated, biopsychosocial model of illness.