What are the general schizophrenia criteria based on the Diagnostic and Statistical Manual of Mental Disorders (DSM)?

DSM Diagnostic Criteria for Schizophrenia

The diagnosis of schizophrenia requires at least two characteristic psychotic symptoms (delusions, hallucinations, disorganized speech, grossly disorganized or catatonic behavior, or negative symptoms) present for a significant portion of a 1-month period, with continuous disturbance persisting for at least 6 months, accompanied by marked social or occupational dysfunction. 1

Core Symptom Requirements

At least two of the following five symptoms must be present for a significant portion during a 1-month period: 1

• Delusions 1, 2
• Hallucinations 1, 2
• Disorganized speech (reflecting formal thought disorder) 1, 2
• Grossly disorganized or catatonic behavior 1, 2
• Negative symptoms (affective flattening, alogia, avolition, anhedonia, attentional impairment) 1, 3

Exception to Two-Symptom Rule

Only one symptom is required if any of the following apply: 1

• Delusions are bizarre in nature 1, 4
• Hallucinations consist of a voice providing running commentary on the person's behavior or thoughts 1, 4
• Two or more voices are conversing with each other 1, 4

Duration Criteria

The continuous disturbance must persist for at least 6 months, which must include: 1, 4

• At least 1 month of active-phase symptoms (the two required symptoms listed above) 4
• May include periods of prodromal or residual symptoms where only negative symptoms or attenuated forms of positive symptoms are present 1

Functional Impairment Requirement

Marked deterioration in one or more major areas of functioning below the level achieved prior to onset is mandatory: 1

• Social dysfunction 1
• Occupational dysfunction 1
• Self-care deficits 1
• In children and adolescents, failure to achieve expected levels of interpersonal, academic, or occupational development 1

Exclusion Criteria

The following conditions must be ruled out before diagnosing schizophrenia: 5, 1

• Schizoaffective disorder and mood disorders with psychotic features - If mood symptoms are present, they must be brief relative to the total duration of psychotic illness 4
• Substance-induced psychotic disorder - Psychosis must not be attributable to the physiological effects of a substance (drug of abuse, medication) 1
• Psychotic disorder due to another medical condition - General medical causes must be excluded through appropriate workup 1
• Autism spectrum disorder or other pervasive developmental disorders - If psychotic symptoms occur in the context of these conditions, schizophrenia is only diagnosed if prominent delusions or hallucinations are present for at least 1 month 5

Clinical Phases of Illness

Schizophrenia typically progresses through distinct phases: 1

• Prodromal phase - Deteriorating function before overt psychosis, including social isolation, bizarre preoccupations, unusual behaviors, academic problems, and deteriorating self-care 1
• Acute phase - Dominated by positive psychotic symptoms and functional deterioration 1
• Recovery phase - Some ongoing psychotic symptoms with confusion, disorganization, and/or dysphoria 1
• Residual phase - Persistent negative symptoms even when positive symptoms improve 1

Critical Diagnostic Pitfalls

Misdiagnosis at initial presentation is extremely common, particularly in adolescents where approximately 50% of those with bipolar disorder are initially misdiagnosed as having schizophrenia due to florid psychosis at onset. 4 Systematic longitudinal reassessment over time is the only accurate method for distinguishing these disorders 4.

Most children reporting hallucinations are not schizophrenic and many do not have psychotic disorders. 1 True psychotic symptoms must be differentiated from psychotic-like phenomena due to developmental delays, trauma exposure, or overactive imagination 1.

Cultural or religious beliefs may be misinterpreted as psychotic symptoms when taken out of context, and clinicians must actively guard against racial biases in diagnosis. 1

Essential Assessment Components

The diagnostic evaluation must include: 5, 1

• Detailed assessment of psychotic symptoms with documentation of type, number, duration, and combinations 5
• Course of illness documentation establishing pattern of symptom development 5, 1
• Evaluation of other symptoms and confounding factors 1
• Family psychiatric history 1
• Mental status examination 1
• Ruling out general medical causes through neuroimaging, EEG, laboratory tests, and toxicology screens as clinically indicated 1

Structured interviews, symptom scales, and diagnostic decision trees should be used to ensure reliability and accuracy of diagnosis. 5