Table 1.

Criteria for Persistent Negative Symptoms

At least moderate severity of negative symptoms, defined on an accepted and validated rating scale

A defined threshold level of positive symptoms on an accepted and validated rating scale

No (or low level of) depressive symptoms on an accepted and validated rating scale

No (or low level of) extrapyramidal symptoms on an accepted and validated rating scale

Demonstrated clinical stability for an extended period of time prior to the start of the study