Background: Psychiatric symptoms are wide-spread in the general population, but have little effect on performance. Deficits in performance and psychiatric symptoms may be the end point of processes common to both, or they may be caused by quite different factors. In this paper we examine the epidemiological distribution of psychiatric symptoms and performance deficits, as indicated by difficulties in activities of daily living (ADL). We hypothesised that ADL difficulties are partly independent of psychiatric symptoms, and that this is reflected in a different demographic distribution.
Method: The household component of the National Surveys of Psychiatric Morbidity was based on a sample of around ten thousand subjects selected at random from the population of Great Britain. Psychiatric symptoms were elicited by lay interviewers using the revised Clinical Interview Schedule. Performance was assessed by asking about difficulties experienced in performing seven types of everyday activity. In this paper, our chosen variables were overall symptom and ADL deficit scores, and these were related to standard demographic variables.
Results: There were significant differences in the epidemiological distribution of psychiatric symptoms and ADL difficulties. In particular, men experienced more ADL difficulties at a given symptom level than women. There were also differences in relation to social class, employment status, marital status, ethnic group and age.
Conclusions: ADL deficits and psychiatric symptoms are related in the general population, and this probably represents common factors in their origin. However, discrepancies in the social distribution of these phenomena suggest there are also aetiological differences. These do not appear to be the result of the impact of physical illness on activities of daily living. Our results emphasise that ADL difficulties should be studied separately, particularly in investigations of treatment seeking.