Symptoms and the perception of disease

Any symptom represents a perception of an abnormal internal body state. The threshold for perceiving the internal body state as abnormal varies and depends particularly on psychological influences. As a result, a symptom can either reflect pathology, whether serious or not, or be generated wholly psychologically. Intuition allowing discrimination between these possibilities is central to the physician's art. Particular difficulty arises in differentiating between those psychologically generated symptoms which are produced unconsciously, often as a result of anxiety or depression, and those that constitute deliberate deception. Such malingering has the unstated intent of accessing a secondary gain, such as welfare benefit. The art of diagnosis includes estimation of whether symptoms resonate with known pathophysiological processes, using history-taking as a story which unfolds logically towards a diagnosis, assessing how a patient reacts to their symptoms compared to neutral matters, detecting exaggeration or falsification, and documenting evidence of psychologically generated abnormalities during examination. Scientific ability is only one of the attributes of a good diagnostician; equally important are abilities to notice things, to weigh up human nature and to recognise dilemmas. Our procedures for selecting medical students and physicians need to assess these skills as well as scientific qualifications.