Mental disorders, particularly schizophrenia and the major affective disorders, are in general strongly associated with social dysfunction. For a long time social dysfunction was considered an epiphenomenon of the disease process. Diagnostic criteria of mental disorders were and still are often derived from the domains of work and social relationships. There are, though, at least two related reasons why social functioning deserves a closer look:

1. 1 There is an increasing trend to treat patients in the community instead of in hospital: this emphasis on community care requires careful evaluation with respect to its consequences. To what extent is survival in the community possible and what is the quality of life like there? Are community programmes better than hospital treatment, and for whom? Therefore, an emphasis on social dysfunction is justified in evaluating the outcome, costs and benefits of community care.

2. 2 There is growing evidence that the time course of symptoms and social dysfunction may vary relatively independently. The social disablement of a patient may be characterised much more by social disabilities than by persistent psychiatric symptoms; the former may call for types of (non-clinical) care that are not readily available. For example, psychosocial rehabilitation focuses on those cognitive and social abilities of the patient which are crucial for a more or less independent life. Therefore, separate measurement is justified for the sake of the right choice of treatment.

Classification of social dysfunction

The standard diagnostic systems, primarily the ICD of the World Health Organization and the DSM of the American Psychiatric Association, offer no adequate solution to the problem of the classification and assessment of the social dysfunction that results from mental disorder. We have to look for other classification systems, such as the International Classification of Functioning, Disability and Health (World Health Organization, 2001), known as ICF, the overall aim of which is to provide a unified and standard language and framework for the description of health and health-related states.

The ICF is the successor of the International Classification of Impairments, Disabilities and Handicaps (ICIDH) of the World Health Organization (1980), which offered a conceptual model to study the long-term consequences of disease or disorder in terms of impairments, functional disabilities and social handicaps, and the effectiveness of healthcare in handling these kinds of problem.