In this paper, we reviewed the available instruments for assessing the negative syndrome of schizophrenia, describing their strengths and weaknesses. Current instruments were classified into two categories according to their content validity and assessment approach as first- or second-generation instruments. The BPRS, SANS, the SENS and the PANSS belong to the first generation, while the BNSS, the CAINS and the MAP-SR belong to the second generation. The NSA can be considered a transitional instrument between the two. First-generation instruments have more content validity problems than second-generation instruments do, as they do not accurately reflect the currently accepted negative syndrome (they do not include all negative symptoms and signs or they include symptoms from other dimensions). They also have more problems relative to the use of behavioural referents instead of internal experiences of deficits when assessing symptoms, which may lead to measuring functioning instead of negative symptoms. Further research needs to be done in this area in order to ensure the evaluation of primary negative symptoms and internal experiences involved in negative symptoms rather than external behaviours.
Keywords: Negative syndrome; Patient outcomes; Psychometric evaluation; Schizophrenia.