2 or more criteria over a 1 month period (or less if treated):

• Delusions = fixed, false, idiosyncratic belief
• Hallucinations = perceptual disturbance, e.g., vision, hearing voices
• disorganized speech
• grossly disorganized or catatonic behavior
• negative symptoms, e.g. affective flattening or avolition

social or occupational dysfunction

Duration:

<= 1 month = Acute Psychotic Disorder

1-6 months = schizophreniform disorder

>= 6 months = schizophrenia

NOT accounted for by:

Mood disorder: affective symptoms -> psychosis; psychosis never present in the absence of mood symptoms;

Schizoaffective disorder: affective symptom + psychosis AND psychotic symptoms in the absence of mood symptoms.

Substance abuse or withdrawal.

Pervasive developmental disorder