What are the diagnostic criteria for schizophrenia?

Diagnostic Criteria for Schizophrenia

The diagnosis of schizophrenia requires at least two psychotic symptoms present for a significant period during a 1-month timeframe, with overall disturbance lasting at least 6 months, and marked social/occupational dysfunction. 1

Core Diagnostic Requirements

Psychotic Symptoms

• At least two of the following must be present for a significant period during a 1-month timeframe:

  1. Delusions
  2. Hallucinations
  3. Disorganized speech
  4. Grossly disorganized or catatonic behavior
  5. Negative symptoms (affective flattening, alogia, avolition) 1

• Only one symptom is needed if:

  • Delusions are bizarre
  • Hallucinations include a voice providing running commentary on behavior/thinking
  • Two or more voices converse with each other 1

Social/Occupational Dysfunction

• Marked deterioration in functioning below previous levels
• In children/adolescents: failure to achieve age-appropriate interpersonal, academic, or occupational development 1

Duration

• Disturbance must persist for at least 6 months
• This period includes an active phase with psychotic symptoms (criterion A) with or without prodromal/residual phases 1
• If duration is less than 6 months but more than 1 month, schizophreniform disorder should be diagnosed 2

Exclusion Criteria

• Schizoaffective disorder and mood disorders with psychotic features must be ruled out
• Substance abuse and general medical conditions must be excluded as causes 1, 3

Clinical Presentation and Phases

Phases of Schizophrenia

• Prodrome: Period of deteriorating function before overt psychotic symptoms (social isolation, bizarre preoccupations, unusual behaviors, academic problems, deteriorating self-care) 1
• Acute Phase: Dominated by positive psychotic symptoms and functional deterioration 1
• Recovery Phase: Follows acute phase with some ongoing psychotic symptoms, confusion, disorganization, and/or dysphoria 1
• Residual Phase: Minimal positive psychotic symptoms but ongoing negative symptoms (social withdrawal, apathy, amotivation, flat affect) 1
• Chronic Impairment: Persistent symptoms that have not adequately responded to treatment 1

Symptom Categories

• Positive symptoms: Hallucinations, delusions, thought disorder, bizarre behavior 4, 5
• Negative symptoms: Affective flattening, alogia (poverty of speech), avolition, anhedonia, attentional impairment 6, 5
• Disorganized symptoms: Disorganized speech, behavior, and attention 7, 5
• Cognitive impairment: Deficits in multiple areas of information processing 7, 5

Assessment Approach

Psychiatric Evaluation

• Detailed assessment of psychotic symptoms
• Course of illness documentation
• Evaluation of other symptoms/confounding factors
• Family psychiatric history
• Mental status examination 1

Physical Assessment

• Rule out general medical causes of psychotic symptoms
• Consider neuroimaging, EEG, laboratory tests, and toxicology screens as clinically indicated 1

Psychological Assessment

• Intellectual assessment may be indicated with clinical evidence of developmental delays
• Cognitive testing may help assess impairment and guide treatment planning 1

Diagnostic Challenges and Pitfalls

• Misdiagnosis at initial presentation is common; longitudinal reassessment is essential 1, 3
• Bipolar disorder with psychotic features can be misdiagnosed as schizophrenia, especially in adolescents 1, 3
• Cultural or religious beliefs may be misinterpreted as psychotic symptoms 3
• Substance-induced psychosis must be ruled out 1, 3
• Developmental disorders in children and adolescents must be distinguished from schizophrenia 3

Treatment Approach

• Comprehensive treatment requires both psychopharmacological agents and psychosocial interventions 1
• Antipsychotic medications are the cornerstone of treatment 1, 7
• Treatment strategies may vary depending on the phase of illness 1
• Early and effective treatment is crucial to preserve cognitive function 7