Functional vs Organic Amnesia
Dissociative Amnesia Organic Amnesia
Overview
Both present as a gap in memory, but the question that separates them is what kind of cause has produced the gap: a psychological one, tied to distressing or unbearable material, or a physical one, tied to damage or disruption of the brain's memory systems. The pattern of the gap itself, not just its presence, is usually the clue.
| Dimension | dissociative-amnesia | organic-amnesia |
|---|---|---|
| Underlying cause | Psychological — a dissociative response to overwhelming or intolerable experience, with no demonstrable brain pathology | Physical — structural or physiological disruption of the brain systems that lay down or retrieve memory (for example, hippocampal damage, head injury, or chronic alcohol-related brain change) |
| What is lost | Characteristically patchy and selective, often centred on the traumatic or distressing period itself, and can extend to autobiographical or personal identity information | Follows a more consistent, physiologically plausible pattern — commonly a difficulty laying down new memories from the point of injury onward (anterograde), sometimes with loss of a period before it (retrograde), but personal identity itself is usually preserved |
| Relationship to identity | Can be severe enough to include loss of one's own name or personal history, occasionally with wandering (fugue) | The person almost always still knows who they are, even when they cannot form new memories or recall recent events |
| Onset and precipitant | Typically follows a specific, identifiable psychological stressor or trauma, and can appear abruptly around it | Follows an identifiable physical event or process — a head injury, hypoxic episode, seizure, or a chronic condition such as sustained heavy alcohol use |
| Course and recovery | Can resolve suddenly and completely once the underlying psychological conflict is addressed or circumstances change | Recovery, if any, tends to be gradual and partial, and follows the course of the underlying brain condition rather than psychological resolution |
| Typical example | A person involved in a violent assault is unable to recall the event, or several years of their life around it, despite no head injury and a normal neurological examination | A person after a significant head injury can hold a conversation and recognise family members, but is unable to remember anything new said to them ten minutes earlier |
Common confusion
Students often assume that any dramatic or extensive memory loss must be organic, since it looks more 'severe.' In fact the opposite pattern is common: dissociative amnesia can wipe out a much larger, more selectively meaningful block of memory — including one's own identity — while sparing the moment-to-moment learning that organic amnesia so reliably disrupts. Severity is not the discriminator; the pattern, precipitant, and relationship to identity are.
Clarifying questions
- Was there any injury, illness, or physical event around the time the memory loss began?
- Is the gap in your memory around a specific, particularly difficult time or experience, or does it affect your ability to remember new things day to day?
- Do you still know who you are, and recognise the people close to you?
Provenance
Class B · tier T1 · lifecycle migrated_candidate
- Casey, P. & Kelly, B. (2019). Fish's Clinical Psychopathology, 4th ed. Ch. 5, 'Disorders of Memory'.