Assessing the efficacy of treatments for the deficit syndrome of schizophrenia.

The primary, enduring negative symptoms found in some patients with schizophrenia have become the focus of clinical treatment trials, but there has been no consensus on the best methods for approaching this area. In future trials, a number of issues need to be considered, including analytic strategies, the limitations in instruments used to measure negative symptoms, and study design. An appropriate design for establishing the efficacy of treatments for the deficit syndrome is proposed.