F06 — Other mental disorders due to brain damage and dysfunction and to physical disease

What is this category?

F06 covers presentations that resemble a 'primary' psychiatric syndrome — a psychosis, a mood disorder, an anxiety disorder — but are judged to be caused by a demonstrable cerebral or systemic physical disease, injury, or dysfunction, in a person whose consciousness is clear and who does not meet criteria for dementia. It exists because a brain disease or a systemic illness can produce almost any category of psychiatric symptom without producing global cognitive decline or clouded consciousness.

Core diagnostic concept

The classification question F06 answers is not "what does this look like — psychosis, depression, anxiety?" but "is there evidence of a demonstrable organic cause with a plausible temporal relationship to this symptom picture, occurring with clear consciousness and without dementia-level decline?" The symptom picture itself can closely resemble F20-F29, F30-F39 or F40-F48 categories; what earns it an F06 classification is the demonstrated organic cause.

Key diagnostic features

A demonstrable organic cause

Objective evidence (history, examination, or investigation) of a cerebral disease, systemic physical disease, or brain dysfunction known to be capable of producing the symptom picture.

A plausible temporal relationship

The onset of the mental symptoms follows the onset (or, for a chronic condition, an exacerbation) of the physical disease, rather than occurring independently or first.

Clear consciousness

Unlike F05, consciousness and attention are not the disturbed feature here — the disturbance is in mood, perception, belief, or another discrete domain.

Absence of dementia-level decline

General cognitive function does not meet the multi-domain decline criteria of F00-F03, though a milder, circumscribed cognitive disturbance ('mild cognitive disorder') is itself one of F06's recognised presentations.

Recovery or improvement with the physical cause, when treatable

Where the underlying physical condition can be treated, the mental symptoms often improve or resolve — supporting, though not required to confirm, the organic attribution.

How to weigh evidence

These learning labels are teaching aids, not official ICD-10 terminology (see Sources and Method).

• supports New, persistent auditory hallucinations beginning shortly after a confirmed diagnosis of a seizure disorder affecting the temporal lobe, with clear consciousness throughout.
• raises alternative A long-standing psychotic illness present for years before any physical disease was diagnosed.
• contradicts or weakens No demonstrable physical disease or brain dysfunction can be identified despite investigation.
• missing and necessary to ask Whether investigations have actually been done to look for a physical cause, or whether the organic attribution is simply assumed.

Duration and course

Minimum duration: Varies by presentation and underlying cause.

Course: Often follows the course of the underlying physical disease, improving as it is treated, though some presentations can persist or recur.

Included presentations

• Organic hallucinosis: persistent or recurrent hallucinations, usually visual or auditory, with clear consciousness and insight often preserved.
• Organic catatonic disorder: catatonic-type psychomotor disturbance with a demonstrated organic cause.
• Organic delusional (schizophrenia-like) disorder: persistent delusions, with or without hallucinations, attributable to an organic cause.
• Organic mood, anxiety, dissociative, or emotionally labile (asthenic) disorder, and mild cognitive disorder: mood, anxiety, dissociative, emotional-control, or mild cognitive disturbances attributable to an organic cause without meeting dementia criteria.

Exclusions and distinguishing presentations

Four-character subtypes (orientation)

A learner should not assign an F06 subtype from symptom content alone; the organic cause and its plausible temporal link must be established first, regardless of which subtype the symptom picture resembles.

F06.0 — Organic hallucinosis

Persistent or recurrent hallucinations, usually visual or auditory, occurring in clear consciousness. (taught for orientation only, not separately assessed in this pilot)

F06.2 — Organic delusional (schizophrenia-like) disorder

Persistent delusions as the dominant feature, attributable to an organic cause. (taught for orientation only, not separately assessed in this pilot)

F06.3 — Organic mood (affective) disorders

A mood disturbance (depressive, manic, or mixed) attributable to an organic cause. (taught for orientation only, not separately assessed in this pilot)

External causes to check first

Categories in this block require that the disturbance is not better explained by another external cause listed below. These short capsules are reminders, not full teaching modules.

Worked example — establishing the organic link before the symptom label

A 45-year-old woman with a confirmed diagnosis of a thyroid disorder develops a two-month episode of persistent low mood, poor concentration, and reduced energy shortly after her thyroid levels were found to be markedly abnormal. She has clear consciousness and no prior psychiatric history. Her mood symptoms have partially improved since starting treatment for the thyroid disorder.

1. Step 1 — Identify the physical disease: a confirmed thyroid disorder is present, a recognised cause of mood disturbance.
2. Step 2 — Check temporal relationship: mood symptoms began shortly after the thyroid abnormality was identified, not years beforehand.
3. Step 3 — Check consciousness and cognition: both are clear, weighing against F05 and against dementia.
4. Step 4 — Check response to treatment: partial improvement with treatment of the physical cause supports, though does not alone confirm, the organic attribution.
5. Conclusion — The presentation is best classified as F06 (organic mood disorder), supported by a demonstrable, temporally plausible organic cause with clear consciousness and no dementia-level decline.

Interactive practice

• Type A A mood change with a medical link Recognition / application · Foundation
• Type F Sorting the organic evidence Explanation and evidence selection · Boundary

Retrieval prompts

Try answering each of these from memory before revealing where to check. Nothing you think or type here is sent or saved anywhere.

1. Without looking back at the page, state the one thing that must be demonstrated, not just assumed, before classifying a symptom picture as F06.

   Reveal answer location

   Check Duration and course, Diagnostic boundary, or the rapid revision card below — the cue you need is one of those, in this category's own already-authored wording.

   I recalled this I need to review this

These self-checks are a personal study aid only, visible to you on this page for this visit — they are not stored and do not affect your mastery dimensions.

Related glossary terms

• Cognitive domain

  A distinct area of mental functioning that can be separately assessed, such as memory, language, attention, planning/executive function, or visuospatial ability. Classifying organic mental disorders often depends on which domain(s) are affected and whether the pattern is isolated or multi-domain.

  Open full glossary entry →

• Insight (clinical)

  The degree to which a person recognises that their experiences (such as unusual beliefs or perceptions) may reflect an illness rather than external reality. Insight can vary and is not itself a classification criterion, but is often noted educationally.

  Open full glossary entry →