Assessment of everyday functioning in schizophrenia: implications for treatments aimed at negative symptoms.

Assessment of functional impairment in schizophrenia is complicated by problems in self-assessment on the part of patients. These problems can be surmounted through the use of appropriate informants and reliable rating scales. In terms of treatment of negative symptoms, not every aspect of functional outcome is adversely impacted by negative symptoms, requiring assessment of multiple aspects of everyday functioning. Failures in the achievement of functional milestones are likely caused by complex combinations of factors, some of which may reside outside the individual. Assessment of sub-threshold milestones (looking for work vs. full time employment) may be the maximally viable strategy and this relies on the use of rating scales. In addition, there are considerable differences across informants in terms of the extent to which their ratings converge with other indices of patient functioning, such as cognitive test performance. Global scores may not adequately capture functioning in different domains, thus suggesting that rating scales with clear separation of social, vocational, and residential functioning may be preferable.