Negative symptoms in schizophrenia. Definition and reliability.

Recently, a renaissance of interest in "negative symptoms," eg, affective flattening or impoverishment of speech and language, has occurred. Although some investigators believe that these symptoms are important indicators of outcome, of response to treatment, and perhaps of a distinct, underlying pathologic process, research on the negative-symptom syndrome in schizophrenia has been handicapped because no standard instrument existed to assess it. This investigation reports on the developed Scale for the Assessment of Negative Symptoms. When symptoms are defined by objective behavioral indices, they have excellent interrater reliability. Furthermore, the five symptom complexes defined by the scale (affective flattening, alogia, avolition, anhedonia, and attentional impairment) have good internal consistency, which indicates that the conceptual organization of the scale is also cohesive.