F20 — Schizophrenia

Concept, in one sentence

A sustained (>= 1 month) psychotic illness with characteristic disturbances of thought, perception and affect, not better explained by mood, organic, or substance causes.

Decisive boundary cues

• Duration >= 1 month, most of the time -> weighs toward F20 over F23.
• Mood symptoms confined to episodes and not central -> weighs toward F20 over F25/affective psychosis.
• Broad disturbance rather than one fixed belief -> weighs toward F20 over F22.

Duration/course cue

At least one month of characteristic symptoms, most of the time.

Nearest alternatives

F21, F22, F23, F25

Common mistake

Classifying from one dramatic symptom (a single hallucination or delusion) without checking duration, mood relationship, or external causes.

Retrieval prompt — one-line memory anchor

What single question would you ask first to separate this case from F23?