Diagnostic Criteria
To make a diagnosis of schizophrenia, the following features must exist:
A. 2 of 5 symptoms are present during a 1-month period: (1) delusions, (2) hallucinations, (3) disorganized speech, (4) disorganized behaviour, (5) negative symptoms
B. Functioning is markedly below the level achieved prior to onset of illness
C. Continuous disturbance for at least 6 months
D. Mood disorders with psychotic features are ruled out
E. Symptoms are not due to substance abuse or another medical condition
"A delusion is a false unshakeable belief, which is out of keeping with the patient's social and cultural background." — Fish's Clinical Psychopathology