Authors' reply

I thank Dr Kaiser for drawing attention to the relationship between cognitive function and quality of life in schizophrenia. Dr Kaiser does not find any relationship with a single test that he uses to assess cognitive function (the WCST) and a German short form of the Lancashire Quality of Life Profile and thus goes on to suggest that there is no relationship. However, there is evidence that such a relationship does exist (Addington & Addington, 1999). Dr Kaiser feels that Heinrichs' Quality of Life Scale (QLS) is an assessment of clinical judgements of negative symptoms but a detailed look at the scale reveals that the four sub-scales of the QLS do indeed measure interpersonal relationships, instrumental role functioning and common objects and activities, among others. It is true that this is an interviewer rating scale and it would be better to have subjective ratings of quality of life. We have indeed carried out such a study and our (as yet unpublished) results show an association between quality of life, as measured by the Lancashire Quality of Life Profile that Dr Kaiser refers to, and measures of cognitive flexibility, verbal ability and verbal memory. Perhaps if Dr Kaiser had used more than one test to assess cognitive functioning in his patients, he may have found an association, as the WCST measures only one aspect of cognitive function. Meanwhile, his point of using subjective measures of quality of life is well taken.