## Diagnostic Duration Criterion for Delusional Disorder **Key Point:** Delusional Disorder requires the presence of one or more non-bizarre delusions for a **minimum of 1 month** (≥4 weeks). ### Temporal Criteria in Psychotic Disorders | Disorder | Minimum Duration | Key Feature | |----------|------------------|-------------| | **Brief Psychotic Disorder** | 1 day – 1 month | Sudden onset, stressor-related | | **Delusional Disorder** | ≥1 month | Delusions only (no hallucinations except mood-congruent) | | **Schizophreniform Disorder** | 1–6 months | Schizophrenia-like symptoms but shorter duration | | **Schizophrenia** | ≥6 months (with ≥1 month active psychosis) | Full psychotic syndrome | | **Persistent Delusional Disorder** | >3 months | ICD-10 equivalent; similar to DSM-5 Delusional Disorder | **High-Yield:** The 1-month threshold distinguishes Delusional Disorder from Brief Psychotic Disorder. If delusions persist beyond 6 months with active psychotic symptoms, consider schizophrenia or schizophreniform disorder. **Mnemonic: "DOSS" for duration milestones** - **D**elusions: 1 month (Delusional Disorder) - **O**ne month minimum - **S**chizophreniform: 1–6 months - **S**chizophrenia: 6 months total (1 month active) **Clinical Pearl:** The 1-month criterion in Delusional Disorder is measured from the **first appearance of the delusion**, not from when the patient seeks help. This is important in retrospective diagnosis. **Warning:** Do not confuse the 1-month criterion for Delusional Disorder with the 6-month criterion for schizophrenia. The key difference is that schizophrenia requires ≥1 month of **active psychotic symptoms** (delusions, hallucinations, disorganized speech/behavior, negative symptoms) within a 6-month period, whereas Delusional Disorder requires only delusions (and no other psychotic features) for ≥1 month. [cite:DSM-5]
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