F05 vs F06
F06 — Other mental disorders due to brain damage and dysfunction and to physical disease
Distinguish an acute, fluctuating disturbance of consciousness from a discrete organic symptom picture (such as hallucinosis or an organic mood disorder) occurring with clear consciousness.
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Show overlap — what both share
Both are attributed to a demonstrable organic or physical cause, and both can include hallucinations, delusion-like beliefs, or mood disturbance as part of the presentation.
Show decisive evidence
- F05 requires disturbed consciousness and attention, fluctuating over the course of a day; F06 presentations occur with clear consciousness throughout.
- F05 has an acute onset (hours to days); F06 presentations can be more sustained or recurrent and are not defined by rapid fluctuation.
- F05's global disturbance affects orientation, memory, thinking and perception together; F06 presentations are typically more circumscribed to one symptom domain (for example, hallucinations alone in organic hallucinosis, or mood alone in an organic mood disorder).
What weakens F05: Stable, clear consciousness and attention at every assessment point, even when hallucinations or mood symptoms are present, weakens F05 and favours a specific F06 presentation instead.
Show duration / course
F05: acute onset, fluctuates markedly within a day, usually resolves once the cause is treated. F06: course follows the specific presentation and underlying disease, without the hour-to-hour fluctuation of delirium.
Show exclusions / context
A single hallucination or a low mood occurring during a period of otherwise-clear consciousness should not be treated as evidence of delirium; check consciousness and attention directly, not just symptom content.
Show information still needed
Whether consciousness and attention are disturbed and fluctuating (favouring F05) or clear and stable (favouring F06), assessed at more than one point in the day where possible.
Show the common trap
Labelling any organic symptom picture with hallucinations or perceptual disturbance as delirium, without actually checking consciousness and attention.
Mini challenge — practise this distinction
Apply the discriminating evidence above to a fresh case before checking the full feedback.