F04 — Organic amnesic syndrome, not induced by alcohol and other psychoactive substances

What is this category?

F04 describes a syndrome of prominent, disproportionate impairment of recent and remote memory, occurring with clear consciousness, while other cognitive functions (general intelligence, attention, language, reasoning) are relatively well preserved. It is caused by brain pathology (most classically affecting the hippocampus and related structures) rather than by alcohol or another psychoactive substance, which are classified separately.

Core diagnostic concept

The classification question F04 answers is not "does this person have memory problems?" but "is memory impairment the dominant, disproportionate feature, with other cognitive domains relatively spared, and consciousness clear?" This is what distinguishes F04 from the broader, multi-domain decline of dementia.

Key diagnostic features

Disproportionate impairment of recent memory

Markedly reduced ability to learn new information (anterograde amnesia), often with variable impairment of remote memory too.

Relative preservation of other cognitive functions

Immediate recall, general intelligence, attention and reasoning are comparatively intact, unlike the broad multi-domain decline of dementia.

Clear consciousness

As in dementia, consciousness and basic attention are preserved.

Confabulation (when present)

Confident reporting of fabricated or distorted memories to fill genuine gaps, without conscious intent to deceive — a classically associated but not universally required feature.

An identifiable organic cause

Classic causes include thiamine deficiency (Korsakoff-type presentations), hypoxic brain injury, herpes encephalitis, and other conditions affecting memory-related brain structures.

How to weigh evidence

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

• supports Marked inability to learn new information since a hypoxic brain injury, with normal conversational ability, attention and reasoning otherwise.
• raises alternative Memory impairment occurring alongside clear deficits in language, praxis or executive function too — this points toward dementia rather than an isolated amnesic syndrome.
• contradicts or weakens Fluctuating consciousness and attention at the time of assessment.
• missing and necessary to ask Whether other cognitive domains (language, praxis, executive function) have been formally assessed and found intact, or simply not yet tested.

Duration and course

Minimum duration: Varies with cause; can follow an acute brain injury (e.g. hypoxia, encephalitis) or develop with chronic nutritional deficiency.

Course: Often persistent once established, though some recovery can occur depending on the underlying cause and how promptly it is treated (for example, thiamine replacement in suspected Korsakoff-type presentations).

Included presentations

• Korsakoff-type amnesic syndrome following thiamine deficiency.
• Amnesic syndrome following hypoxic brain injury or herpes encephalitis, with other cognition relatively preserved.

Exclusions and distinguishing presentations

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 — isolating the memory deficit

A 52-year-old man recovering from a cardiac arrest with a period of hypoxia is unable to recall having met his care team minutes earlier, though his conversation is fluent, his reasoning on non-memory tasks is intact, and his attention span during testing is normal. He sometimes offers confident but inaccurate accounts of recent events when a gap in memory arises.

1. Step 1 — Check breadth: memory is severely affected while language, reasoning and attention are formally assessed and found intact — an isolated deficit.
2. Step 2 — Check consciousness: he is alert and attentive throughout assessment, weighing against delirium.
3. Step 3 — Note confabulation: confident but inaccurate filling of memory gaps is consistent with, though not required for, this syndrome.
4. Step 4 — Check cause: a hypoxic brain injury is a recognised and plausible cause.
5. Conclusion — The presentation is best classified as F04, supported by an isolated, disproportionate memory deficit with preserved consciousness and other cognition, and a plausible organic cause.

Interactive practice

• Type A Everything but the memory Recognition / application · Foundation
• Type B Just memory, or something broader? Boundary / differential · 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 you must confirm about other cognitive domains before classifying a memory problem as F04 rather than dementia.

   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

• Confabulation

  The unintentional production of fabricated or distorted memories, without the intent to deceive, sometimes seen alongside significant memory impairment. Confabulation is a possible accompanying feature, not itself a required or defining criterion of any single category.

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• 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 →