Delusions in depth — Psychiatry Handbook

Theme — persecutory, referential, grandiose, jealous (Othello), erotomanic, guilt, nihilistic (Cotard), somatic, control/passivity, misidentification (Capgras — familiar person is an impostor; Frégoli — strangers are a known person in disguise).
Conviction — a spectrum; quantify at baseline because falling conviction is an early, sensitive marker of antipsychotic response.
Bizarreness — physically impossible/implausible (weakly toward schizophrenia) vs non‑bizarre (delusional disorder).
Systematisation — encapsulated and internally elaborated (delusional disorder) vs fragmentary (schizophrenia).
Mood congruence — congruent (grandiose in mania; guilt/nihilism in psychotic depression → affective psychosis) vs incongruent (schizophrenia‑spectrum).
Primary vs secondary — primary (arising de novo, e.g., a delusional perception) vs secondary (understandable from mood/hallucination/cognitive change).

Delusion vs over‑valued idea vs obsession: conviction + fixity + reality attribution (delusion) → resisted, ego‑dystonic, recognised as one's own (obsession) → dominating but not fully fixed, reality testing partly intact (over‑valued idea).
Shared delusion (folie à deux): delusion transferred within a close relationship; often resolves on separation — treat the primary case and address the dyad.

Missing mood congruence and thereby mislabelling an affective psychosis as schizophrenia — the treatment (antidepressant/mood stabiliser + antipsychotic ± ECT) differs.
Reflexively assuming a culturally normative belief is delusional.

🎯 Track conviction numerically — it's your earliest quantitative signal of response.
🩺 A single encapsulated non‑bizarre delusion with preserved function ≠ schizophrenia → think delusional disorder.

Next → The same phenomenological rigour applied to perception (Concept 11).

Educational only — not a substitute for clinical judgement, supervision, or local guidelines.

Theme — persecutory, referential, grandiose, jealous (Othello), erotomanic, guilt, nihilistic (Cotard), somatic, control/passivity, misidentification (Capgras — familiar person is an impostor; Frégoli — strangers are a known person in disguise).
Conviction — a spectrum; quantify at baseline because falling conviction is an early, sensitive marker of antipsychotic response.
Bizarreness — physically impossible/implausible (weakly toward schizophrenia) vs non‑bizarre (delusional disorder).
Systematisation — encapsulated and internally elaborated (delusional disorder) vs fragmentary (schizophrenia).
Mood congruence — congruent (grandiose in mania; guilt/nihilism in psychotic depression → affective psychosis) vs incongruent (schizophrenia‑spectrum).
Primary vs secondary — primary (arising de novo, e.g., a delusional perception) vs secondary (understandable from mood/hallucination/cognitive change).

Delusion vs over‑valued idea vs obsession: conviction + fixity + reality attribution (delusion) → resisted, ego‑dystonic, recognised as one's own (obsession) → dominating but not fully fixed, reality testing partly intact (over‑valued idea).
Shared delusion (folie à deux): delusion transferred within a close relationship; often resolves on separation — treat the primary case and address the dyad.

Missing mood congruence and thereby mislabelling an affective psychosis as schizophrenia — the treatment (antidepressant/mood stabiliser + antipsychotic ± ECT) differs.
Reflexively assuming a culturally normative belief is delusional.

🎯 Track conviction numerically — it's your earliest quantitative signal of response.
🩺 A single encapsulated non‑bizarre delusion with preserved function ≠ schizophrenia → think delusional disorder.

Next → The same phenomenological rigour applied to perception (Concept 11).

10. Delusions in depth