- Schizophrenia clinical symptom burden severity defined by the following: a Brief Psychiatric Rating Scale (BPRS) Conceptual Disorganization item score ≤ 4; and a BPRS Hallucinatory Behavior item score ≤ 5, or an Unusual Thought Content item score ≤ 5. Either Hallucinatory Behavior or Unusual Thought Content, but not both, may have a score of 6 (but not > 6).