The interaction of psychological and physical disorders and their treatment Francis Creed Abstract Patients consult doctors for symptoms that may represent well-recognised physical disease or psychiatric disorders but many patients request help for bodily symptoms that may result from a combination of these disorder and do not appear to have a clear “physical” or “psychological” origin. The interaction of physical and psychiatric disorders will be reviewed to show how recent research can improve the care that patients receive. The interaction of depression and physical illness will be considered in heart disease to show how depression leads to the development of heart disease, and vice versa. The presence of both disorders leads to a poor outcome in heart disease patients. Guidelines concerning the treatment of depression in people with chronic physical illness have been produced recently by UK National Institute for Health and Clinical Excellence. A recent treatment study has raised the prospect that depression may be prevented in newly diagnosed cancer patients. Although mildly bothersome bodily symptoms are very common, a small proportion of the population report numerous such symptoms, which impair functioning and may lead to frequent consultations with doctors. Psychiatric and physical disorders are both associated with an increased number of bothersome bodily symptoms but neither can fully explain such symptoms. Both genetic and environmental risk factors have been implicated and recent research suggests that they may respond to a variety of psychological treatments.