Hierarchical patterns in the distribution of psychiatric symptoms.

The occurrence of hierarchical patterns in the incidence of psychiatric symptoms in individual patients and community subjects is investigated. Data obtained from interviewing a sample of people from the population of Camberwell, south-east London, using the Present State Examination (PSE), were analysed as were similar data concerning three series of patients referred to different kinds of psychiatric service. The population series showed that each of the common PSE symptoms tends to occur in association with other symptoms. Symptoms that are rarer in the general population are associated with the presence of many other symptoms or with other symptoms present to a severe degree. The rarer the symptom, the higher is the total symptom score indicated by its presence. The more indicative symptoms are also associated with a measure of social disability derived from the MRC Social Performance Schedule, which asks about serious problems in functioning in each of 8 role areas. The implication of this study is that total symptom score is a valid measure of the current severity of the disorder. The hierarchy model of Foulds & Bedford (1975) is discussed and is shown to be a more specific formulation of the same idea. Investigation of the referred series confirmed these conclusions. When compared with community subjects, patients tend to have a much higher total PSE score; they display symptoms which are very rare in the community; they tend to be disabled socially. However, they are less likely to fulfil the requirements of a specific formulation for the presence of minor symptoms. In particular, only about half of psychotic subjects display specific neurotic symptoms, although virtually every subject with 'specific' symptoms of some sort displayed non-specific neurotic symptoms.