Category: F20 F21 F22 F23 F24 F25 F28 F29
F20 — Schizophrenia: facilitator sheet
Teaching objective
The classification question F20 answers is not "does this person have unusual beliefs or experiences?" but "is there a sustained pattern of characteristic psychotic disturbance, lasting long enough and clear enough to distinguish it from a brief reaction, a mood episode with psychotic features, or an organic/substance-induced state?" Schizophrenia is defined educationally here as a sustained pattern, not a single symptom, and not a personality trait.
Choose material
Worked example · Case: A change over two months · Case: Odd for years, or newly unwell? · Case: One week in · Case: New information changes the picture · Case: Just one voice · Case: Sorting the evidence
Worked example
Show scenario
A 24-year-old presents with a two-month history of hearing two voices that discuss him in the third person and comment on his actions, alongside a fixed belief that a local radio station is broadcasting his thoughts. His family reports he has become withdrawn, stopped attending classes, and shows little facial expression. There is no history suggesting a manic or depressive episode, no relevant substance use, and no medical illness identified.
Reveal step 1
Step 1 — Check duration: symptoms have been present for about two months, most days, which satisfies the one-month minimum used to separate F20 from F23.
Reveal step 2
Step 2 — Check for a mood explanation: no manic or depressive episode is described, and the psychotic features are not confined to a mood episode, which weighs against F25 or an affective disorder with psychotic features.
Reveal step 3
Step 3 — Check breadth of disturbance: there is more than one fixed belief theme plus third-person commentary voices plus negative symptoms (blunted affect, withdrawal, functional decline) — a broader picture than a single circumscribed delusion, which weighs against F22.
Reveal step 4
Step 4 — Check for organic/substance causes: none reported; if this vignette is being used for real teaching, the absence of a medical work-up should itself be flagged as missing information in a real clinical context, even though it is stipulated as absent here for classification purposes.
Reveal step 5
Conclusion — The presentation is best classified as F20, supported by duration, breadth of disturbance, and lack of a mood or external explanation, while the boundary against F23, F25 and F22 has been explicitly checked rather than assumed.
Comparison points
F20 is distinguished from its nearest neighbours mainly by three variables: duration and course (against F23), the centrality of mood (against F25 and affective disorders with psychotic features), and whether there is one circumscribed belief system rather than a broader disturbance (against F22 and F21). See the linked comparisons for the full reasoning.
Misconception prompt
Choosing from one dramatic symptom: "If there's a hallucination or a delusion, it must be schizophrenia."
Ask the class why this reasoning fails before revealing the explanation below.
Reveal why it fails
Hallucinations and delusions appear across many categories in this block (and outside it) — F22, F23, F25, mood disorders with psychotic features, substance-induced states, and organic conditions can all produce them. Schizophrenia is defined by a sustained pattern across duration, breadth of disturbance, and exclusion of other causes, not by the mere presence of one psychotic-quality symptom.
Discussion prompts
Prompt 1
Without looking back at the page, state the one piece of duration information that most often separates F20 from F23.
Prompt 2
Name one feature that would make you seriously consider F25 instead of F20.
Prompt 3
Explain in one sentence why a single unusual belief is not, by itself, enough to classify a case as F20.
Summary
A sustained (>= 1 month) psychotic illness with characteristic disturbances of thought, perception and affect, not better explained by mood, organic, or substance causes.