DSM Criteria for Schizophrenia
The diagnosis of schizophrenia requires at least two of five core psychotic symptoms present for a significant portion of a 1-month period, plus functional decline and a total duration of at least 6 months, after ruling out mood disorders, substance use, and medical conditions. 1
Core Diagnostic Criteria
Criterion A: Psychotic Symptoms (Active Phase)
At least two of the following must be present for a significant portion of time during a 1-month period:
- Delusions
- Hallucinations
- Disorganized speech
- Grossly disorganized or catatonic behavior
- Negative symptoms (affective flattening, alogia/poverty of speech, avolition)
Important exception: Only one Criterion A symptom is required if any of the following are present:
- Bizarre delusions
- Hallucinations consisting of a running commentary on the person's behavior or thoughts
- Two or more voices conversing with each other 1
Criterion B: Social/Occupational Dysfunction
For a significant portion of time since onset, functioning in work, interpersonal relations, or self-care has markedly deteriorated below the pre-illness level. In children and adolescents, this manifests as failure to achieve expected levels of interpersonal, academic, or occupational development 1.
Criterion C: Duration
Continuous signs of disturbance must persist for at least 6 months. This 6-month period must include:
- At least 1 month of active-phase symptoms (Criterion A)
- May include periods of prodromal or residual symptoms
If duration is less than 6 months, diagnose as schizophreniform disorder instead 1.
Prodromal/residual phase symptoms include: marked social isolation, occupational deterioration, peculiar behavior (food hoarding, poor hygiene), blunted or inappropriate affect, tangential or circumstantial thinking, poverty of speech content, odd beliefs or perceptions, and anergia 1.
Criterion D: Schizoaffective and Mood Disorder Exclusion
Schizoaffective disorder and mood disorders with psychotic features must be ruled out. This is particularly critical in adolescents with bipolar disorder, as manic episodes frequently present with schizophrenia-like symptoms at onset. Continued longitudinal follow-up may be the only accurate method to distinguish these disorders 1.
Criterion E: Substance/Medical Condition Exclusion
The disturbance is not attributable to the physiological effects of substances (drugs of abuse, medications) or another medical condition 1.
Critical Clinical Pitfalls
Bipolar disorder misdiagnosis: Adolescent manic episodes are notorious for mimicking schizophrenia at presentation. Systematically reassess the diagnosis over time—this is not optional 1.
Duration requirement: The 6-month threshold is absolute. Premature diagnosis leads to inappropriate long-term treatment planning and prognostic discussions.
Negative symptoms often overlooked: Affective flattening, poverty of thought, and avolition count toward Criterion A but are frequently underrecognized compared to positive symptoms 1.
Comparison with ICD-10
ICD-10 allows diagnosis once sufficient symptoms are present for 1 month or more (rather than 6 months), representing a key difference from DSM criteria. High diagnostic agreement exists between DSM-IV and ICD-10 in adolescent populations 1.